I agree that BTC has little inherent value, it hasn't turned out all that useful. Even if you believe the advantages of crypto are worth all the disadvantages there are blockchains that are much better.
But similar things can be said about many things, and some commodities are able to sustain their bubbles for decades or centuries. Gold is going strong for millennia, with a price far exceeding its practical value. BTC probably won't last that long, but unless it's disrupted by legislation it might still have decades left in it.
The bitcoin network is extremely valuable. Trustless money is important in a world where all other currencies are created, controlled, and manipulated by governments. We know humans are prone to make poor choices, commit crimes, etc. Especially governments. Why do we allow them to create money when and how they want?
But similar things can be said about many things, and some commodities are able to sustain their bubbles for decades or centuries. Gold is going strong for millennia, with a price far exceeding its practical value. BTC probably won't last that long, but unless it's disrupted by legislation it might still have decades left in it.