There are companies offering completely useless software 'solutions' that don't even do their useless task well and many of them have stock prices that have grown 100% + since the bailouts, even if they haven't updated their technology since before then. How is the value of BTC more fake than that?
The difference is that if management of the average publicly traded stock shopped it around, they could probably find a buyer for 50% or more of current market cap. Maybe not for the biggest companies like Amazon and Apple. If a substantial fraction of BTC owners tried to exit, they'd have more trouble getting close to nominal value.
For something like this a metric known as enterprise value is used. Assets - cash + debt AKA the takeover price. You can find these numbers on the company's balance sheet. The average company is traded at something like 3.5x their book value (Assets - debt). The market value of a company is likewise some multiple of their EV.
That is understating the situation quite a bit. Volume is so non-existent that basically any attempt at exiting at all would crater the price.