I suspect this thought experiment is overly simplistic to the point of not being useful. Person A has $50k worth of BTC. Person B has $50k worth of cash (some % of which they got from the stimulus). So now 'the room' has $100k in assets. A and B exchange their assets. A+B still equals $100k. $BTC drops by $15k. A+B=$85k. There is now $85k in assets in the room. $15k was lost.
You can expand the model to include all BTC buyers and sellers. It doesn't change the fact that US currency was devalued to generate an economic stimulus. A meaningful % of that stimulus was spent into 'the room.' The value of certain assets in the room was massively overstated and crashed. The stimulus money cannot be recovered, but Americans must live with the inflation and other impacts for many years.
