One thing though is that is unlikely that everyone would cash out below a certain price for a stock can be sold for parts. There would be at least some people realizing that they might as well hold, liquidate the company and make a profit out of it. So in practice there's a floor for the stock price (as long as assets > liabilities or similar).

That's not the case of BTC. Its value is completely depends on confidence. At no price can you be sure that you'll make a profit, you can only guess that it'll go back up, so there's no such floor.