TL;DR cryptocurrencies can be put in two categories:

Bitcoin / bitcoin wannabes and Altcoins

Altcoins have a lot in common with fiat tbh.... ETH, SOL, DOGE, etc are centralized. There's a man behind the curtain. There's an admin key. Whoever is in charge can edit it, add more or less of it, freeze it, etc. In many cases, doing something like that might be detrimental to the currency itself, but perhaps the crypto company gets taken over by the government or a malicious actor. Game over. Supposedly there's a nice comfy security cushion with the fact that transactions can be reversed and you can do lots of cool things like buy NFTs, and perhaps there will be a few altcoins that stand the test of time because of their niche use-cases. But if we're talking about resilience to become a global currency, co-opted coins don't cut it.

That leaves us with TRULY decentralized currency. Bitcoin is digital scarcity. It's immutable information. There's no man behind the curtain, there's no admin key. In that sense, it's like physical gold. You can't co-opt gold. There can really only be one successful currency in this space. A) Bitcoin is the most secure option, B) bitcoin's success is very natural / darwinistic, which will continue to be the case until it takes over (every attempt to be a "better bitcoin" took a lot of money and marketing from powerful actors, and they've all failed), and C) so far the market agrees.