There is a little bit of real value in having a rail that is hard to block, so you can move money across borders or around account freezes, sanctions, or runaway inflation. But that probably only justifies a tiny slice of the current price.
Most of the rest is speculation.
Fiat is different. A national currency is tied to the economy that uses it. Wages, rent, groceries, taxes, all live in that unit. Even if it crashes on FX markets you can still use it inside that country to buy local goods and services, and over time prices and wages shift along with it. The currency may fall against the dollar, but the local cost of living in that currency moves with it too.
The dream was that crypto gets adopted economically in a similar fashion, and even globally, that simply didn't happen, so it ended up just being gambling.