That is a very simplistic way of looking at it... but there is much more to it mining than a simple input/output view...
I dont know if you are aware of the amount of people mining.... just from SlushPool there are over 15,000 active users, all of which have varied and hashrates... which means different payout ratios and varying amount of Bitcoin rewards... Some miners do not even withdraw their BTC for months, let alone sell.
Just because there are 1800 BTC created everyday, doesnt means there needs to be $20M+ of new investment everyday...
However, there is always a cost associated with generating 1800BTC. Electricity Cost/hardware depreciation etc etc... this cost would need to be paid out regardless...
Any moron can make something difficult, it takes intelligence to make something simple. On average yes 1800 btc are sold per day. Yes there is an inventory, but it will eventually get sold +older coins will get sold during ridiculous highs.
At 13k yes you will need $20M+ to sustain the price. That is why it dumped so fast. It was clear market manipulation up.
I made this system to help people understand the reality of bitcoin. It is designed to help people find the right time to buy, and make money off the morons buying "on the moon".
Much love,
Aaron