If you can't point to any math to justify a given price, there is no intrinsic value. Thus price is only driven by speculative factors.
With stocks there are earnings that can be distributed back to shareholders. This is a measurable and explainable fundamental factor.
Real estate has rents... Bonds have coupon payments. Crypto has nothing. Though some will pay you "yield" by diverting money from newer entrants... Aka pyramid-esque structure
As an investment vehicle, it's exactly as you say; there is no fundamental value it represents. As a currency, it has no governmental backing, and while it's possible to trade in currencies, the profit lies in the trade, and the various differing rates of exchange, NOT in the underlying currencies themselves. No one holds currency expecting deflation to make them better off.
Crypto has none of these. And if it's a good investment, then it's definitely not a good currency
The Bank of England would like a word with you.