Cryptocurrencies have no alternative. If it not decentralized then it had lost its uniqueness and beauty. The reason for the rise in the popularity of Bitcoin is because of its security and decentralization. If you want to kill the Bitcoin (unlikely), kill its uniqueness.
I disagree to that, the majority of people using bitcoin recently is because of its value, bitcoin price has been appreciating over time, it is an appreciative asset, that is why people are using it. Many people are using centralized wallets and exchanges today and do not know about noncustododial wallet or decentralized exchanges, they use what they heard from friends or what hey googled online.
Take it also or you leave it, bitcoin is an alternative to fiat, it can be used for means of exchange, but it is unique and more of an asset which helps in its adoption.
The best is to have full control, making use of noncustododial wallet and exchanges, but I just used this to explain what is actually happening as people are using bitcoin just like novices.