The 'value' behind the stock is discounted (current vs future value of money) expected/estimated revenue steam. i.e. business like Microsoft that collects its 75% margin on Azure , its Office 365 payments, its GamePass revenue streams ($15 per user per month per however many tens of million people they signed up), its licensing fees, etc .This is behind the value of the stock. Unless the company disappears (fraud, massive risks not handled correctly ,etc) - the fluctuations of the stock are less relevant.
The I-Bonds , the 'value' behind it is the taxing power of US Government . Good luck arguing with that .
The 'value' behind some e-coin (dogecoin, catecoin, makeupsomenameecoin, ) ? Who knows. What taxing authority is supporting it? What revenue stream? How stable is that revenue stream?
There are also MASSIVE regulatory compliance requirements for a listed stock/corporation , including what and how goes into fillings, laws like SOX in place to make relevant people personally responsible for signing financial results, etc.
Do fads happen? Yes, of cause - however generally, the value tracks revenue streams and adjusts as every cycle shown.
Comparing heavily regulated stock market to totally unregulated 'crypto' , I am not sure it is fair at all to crypto.. just further proves how much of bad idea it is in terms of investment..
may be the block chain itself would be useful for something in the future. the current first iteration of crypto is totally not.. unless you ran ransomware business or deal with illegal drugs..