I think so too,
I have a suspicion that the batches they release to the public are just the leftovers...

While I agree with everything else in your post, the statement above is troubling me. It has to be a lot more than 7000 units in 60 days. Nvidia and AMD for example both produce millions of GPU's each month.

Lets do some research:
Bitmain's S9 production numbers are not truly known but we can make some educated guesses, we know for example that Bitmain is currently buying 100,000 ASIC chip wafers from TSMC monthly (source: https://www.digitimes.com/news/a20180130PD208.html?mod=3&q=TSMC).
You get roughly 5158 chips out of one wafer so at 189 chips per S9, that's 27 S9's per wafer (source: https://medium.com/@jimmysong/just-how-profitable-is-bitmain-a9df82c761a)
This means that with the 100,000 wafers they order each month, they can make 2.7 million S9's monthly!

I'm sure not all those chips/wafers are destined for S9's but it makes the 857,000 S9's over 60 days you calculated above sound much more plausible.

I am well capable of reading, here’s what was said:

Have you had a look at the curve over the last 2 years: https://data.bitcoinity.org/bitcoin/difficulty/2y?t=l
As HoleShot correctly points out in the previous post, it’s following a logarithmic function.
What you are doing is on this graph, you’re drawing a straight line between the first and last point, you’re then extending that line to predict the future. Surely you can see that the slope of the line you’re drawing is not following the latest trend of the curve.

Perhaps this one: https://blockchain.info/charts/hash-rate
or this one: https://bitinfocharts.com/comparison/bitcoin-hashrate.html#1y
or this one: https://www.coinwarz.com/network-hashrate-charts/bitcoin-network-hashrate-chart,
or this one: https://data.bitcoinity.org/bitcoin/hashrate/6m?c=m&g=15&t=a
…
Which one are you looking at?

Good.

Not sure why you would expect that, growth rate has always increased.

Very wise decision Sir, instant 12k profit :-)

On the contrary sir, I understand perfectly. That's what started this whole thing, just look at my first posts in this thread.

As I mentioned many times before in this thread, I was mining with my beloved S9 till just over a month ago.
I saw they were selling on Ebay for ridicules prices and did some calculations to see if my miner would still make me as much money as the profit I was able to sell it for at that time. I posted the resulting spreadsheet here, the outcome was obvious, SELL!
So after mining for a while and making some descent BTC, I ended up selling my 6 month old miner for $2600 more than I originally bought it. I'm now investing that profit directly into crypto (not BTC at this time but that's another discussion).

Anyway, since then, miners on Ebay have halved in price. I sold at the peak it seems.

So the question for you is, do you sell your miner(s) today and probably be able to get your full original investment back (that's what they're selling for roughly now on Ebay) on top of the BTC you earned so far, or,
do you wait a few months and sell it/them for perhaps a couple of thousands less? And how much BTC will your miner mine in the meantime to make up for that difference.
It's a hard decision in any case, mining is just fun, I know! Yet, rationality should prevail.

I had not even seen that last 10% increase, we can add it to the list :-)

A 1% increase every 18 days, you guys are kidding, right?

2 weeks ago it increased by 16.8%,
2 weeks before that it increased by 15.3%,
2 weeks before that it increased by 3.0%,
2 weeks before that it increased by 17.7%
2 weeks before that it increased by 18.1%

In the last year alone, difficulty has increased by 490% (last Feb it was 0.441T, now it’s 2.6T), and it is now increasing at a rate much faster than that.
So I don’t know how you guys justify the numbers above.

And what’s this about “difficulty will level out”? Why would you think that?
You are aware that in the almost 10 years of bitcoin history, THAT HAS NEVER HAPPENED!
In fact, apart from the odd blip here and there, difficulty has ALWAYS increased and the rate at which it has been growing has ALWAYS been increasing as well.

Just look at the data:
https://data.bitcoinity.org/bitcoin/difficulty/5y?t=l

Saying it will magically start to flatten out is true wishful thinking in my opinion.
Anyway, keep buying those S9’s every time Bitmain releases a batch…

Yep, but under that scenario you're still better investing the money you pay for a miner directly into bitcoin now, if all you're banking on is BTC value to go up.
In a year's time you'll be left with more BTC (valued at $30k),

You do the math, how much BTC can you buy now for the price of a miner? Will it make that much BTC this year? The answer should be obvious.

First of all it's about ROI, not profitability,
Yes an S9 that is running now and has already paid for itself will be profitable for a little while longer, however, buying an S9 now is silly, the numbers just do not show they will ever ROI based on current network growth rate.

And if an S7 was "profitable" (not ROI'ing) until recently but now it's not anymore, that should tell you something shouldn't it?

How much you earn from your miner is determined by the miner's hashrate vs. the total network hashrate.
An S9's hashrate is about 2.8 times that of an S9, that means that the total network hashrate has to just get multiplied by 2.8 for an S9 also to become unprofitable.
As I mentioned in the post above, the network hashrate has doubled in the last 2 months, and it is growing even faster now, much faster. So how long do you think an S9 will remain profitable for?
Just do the math!

I'm sorry but if all you are doing is looking at the online mining profitability calculators or you're just projecting your earnings today forward to estimate what your miner will earn you over the next 224 days, your are (and I'll say this as nice as I can) letting yourself be mislead.

When I had my S9 running in December (I sold it since then), those online calculators were telling me it would make me about 1 BTC/year. Now if I enter the numbers it's less than half that!
That is because the total network hashrate has doubled since then. If you don't understand the significance of this you should look up the Legend of the Ambalappuzha Paal Payasam.

And guess what, it will almost certainly do so again, at faster and faster rates!
How do I know this you ask? Well I don't know this for certain, it's an estimated guess purely based on the fact that THAT's WHAT IT HAS ALWAYS DONE!
So you can say we're on drugs for saying what we're saying but you're the one betting against the network hashrate doing what it has always done.

Look at the forecast tables I created, I posted them a few pages back, they show you exactly what is likely to occur and what that will mean for your earnings (and beware, at the time BTC was $11500). At the current

This is wishful thinking.
BTC value cannot be forecast but you can make some pretty good predictions about total network hashrate and difficulty, I’ve shared mine on various occasions in this thread and even the best case scenarios don’t show an S9 to be a good investment currently, worst case scenario shows the S9 to be money down the drain.
It’s been over a month since I built those forecast and so far the total network hashrate is growing even faster than my original worst case scenario. That should tell you something.
Anyway, you can find the work a few pages back in this thread, check it out.

That is true, and if you have a miner that has already paid for itself then you can still do this for a while. But you're probably still better off selling it now and buying BTC with the money as you probably won't be able to once it becomes unprofitable (very soon).
A recent S9 purchase though (or future purchase) is currently not predicted to ROI, thus it will be mining at a loss at current BTC value and so if you’re just doing it because you think the value of BTC will go up it is better to use the money to buy BTC now than buy a miner that makes BTC, you’ll end up with more BTC in the end.
That was the whole point of the argument.

Why would you think I’m not?

That’s the wisest thing you can do at this stage. It would be even better if you could sell them now as a “pre-order” with promised March delivery although that concept does not seem to fly anymore either these days.
I’ve been monitoring the price of miners selling on Ebay since I sold mine last month and they have been dropping faster than the value of BTC.
Every miner now is selling for a couple of hundred bucks less than the one before.

This has been brought up many times before. It's just a fallacy.
Once you get to a point where your miner is not profitable based on today's value of bitcoin (either it's not going to ROI if you recently purchased it, and/or, it's costing you more power than what it generates), it's always better to invest your money directly into BTC if what you're banking on is BTC value to go up. That's just a fact.

I’ve done my best trying to demonstrate this obvious fact to people in this thread, simple hashrate forecasts show we’re entering a period of negative profitability for all of us.
Yet, people cannot see what they don’t want to see, once emotionally invested it’s hard to remain rational. Hence S9’s are still selling like cupcakes every time a batch is released...

This is a very common scam that was happening on Ebay, Aliexpress etc. at the end of last year, less so now it seems.
What they were doing is claim to have a miner on order on a batch due for delivery very soon but what they really do is order a miner once they have your money. Then it’s just a game of stalling and excuses.
Basically you end up just paying the guy a huge commission to orde a miner from Bitmain for you on a future batch.

Well, if you believe that insults and unfounded allegations can serve as arguments in a discussion you have already lost.
In a discussion you bring facts, figures and evidence to the table if you want to make your case.
Especially if you want to make predictions about the future and/or question someone else's!

I'm sorry but I have seen none of this coming from your end of the table.

This is another emotional reaction with no real content or arguments against what I have put forward here.

I'm not telling anybody to do anything, I'm just pointing out what should be obvious.
Even without this spreadsheet, if you owned an S9 beginning of December as I did, the online calculators were predicting I'd make about 1BTC/year, if you look now it's half that! (which is in line with network hashrate doubling since then)

But back to my calculations.
Again, if you see any flaws or bad assumptions in what I am showing here, just point it out.
What you are doing is just making unfounded allegations.

I am not hiding or fudging anything, I have no "plan", but I am very willing to discuss what I am putting forward here related to the continuing (or lack there of) profitability of an S9 and whether you should really own one now and/or invest in one or more.

I have no skin in the mining game anymore,
But you obviously do, hence you’re reacting emotionally and ignoring the numbers.
If there is a flaw in my calculations or I’m basing them on wrong assumptions, please point this out specifically rather than make unfounded assertions/allegations, the spreadsheet is still available to download and what I’ve done is pretty straightforward.

Because I like to say "I told you so". 
But seriously, if you look at what I posted, they are not "predictions" they are a best case scenario, worst case scenario and current trend scenario.
I'm just pointing out that what is happening is far worse than my original "worst case scenario".