Let's say that a hypothetical person got into BTC in early 2016, and such person had a salary that when from $10k to $30k in the past 7 years, so if such person had not made too many other investments, maybe such person had made some mistakes along the way, but maybe ended up accumulating 2 bitcoin.... so it could be possible that such person never sells all of his/her bitcoin but instead maybe shaves off 10% of his/her then holdings at various points in time.. at $100k, at $150k, at $250k.. .. so even if there might be questions of BTC price direction, the amount of BTC that is sold is less than the profits that had been made in the integers.. and surely you could look at 2 BTC and you could say that from $30k to $100k the profits had gone up $70k per coin, so a total of $140k for that price move, so if there is a decision to sell 50% or less than the profits, you will never run out of bitcoin and you will still be able to skim off pretty decent profits to either be able to buy back if the BTC price goes down or just use such value for consumption purposes.. .
From a $10k salary per month, if the investor invests $2k per month for 3 years, it is a total of $72k.
You are taking this to a whole different place when you change the example from yearly to monthly. I was referring to an annual salary that increased from $10k to $30k over 7 years in order to allow for my point to be made through such hypothetical regarding how such BTC accumulation might affect a person if the BTC price were to go shooting up and maybe certain points in which some BTC might be shaved off at various price points along the way in order to not necessarily devolve into all or nothing thinking when it comes to BTC portfolio management - which from my perspective starts to seem more like gambling rather than investing, when guys seem to be considering price points in which they are selling all or even a vast majority of their BTC holdings..
For now, about 2 points something BTC, the investor might decide to sell some specific amount that he can use for important something like starting another investment because that is also a good idea.
When a salary increases to $30k, the investor can decide to increase his investment to a good amount like $5k or above, so he can have multiple folds for the 4 years and investing $5k for 4 years will give you a good amount of BTC at the end.
Again.. your hypothetical seems to be misreading what I had said, even though I don't really disagree with some of your points, but the numbers that I had been trying to use don't work anymore if you are changing that $30k from annually and into monthly.