If you believe crypto is purely speculative, maybe you can argue it's a near perfect measurement of excess liquidity sloshing around the financial system
It seems like stable coins would track the excess liquidity people are hoping to reinvest and all other crypto currencies track the amount of excess people are willing to just lose.
Only when its potential upside vs risk is better than any other option. As is with any other investing (though probably a bit more buffered since it’s relatively scary investing to anyone even mildly risk averse).