Here's a good answer:
So having your own blockchain domain and even using it as a method of login is illegal and centralised now? [0] ENS is a good existing example and concept 'so-far' of a valid use case, even when I disagree with it being implemented on Ethereum.
As for payments, cryptocurrencies that have blockchains like Bitcoin should be dismissed in the long term. Regulated stablecoins seem better for that purpose these days.
Another use case would be protection from inflation - if you're in a country which prints money carelessly or for political reasons.
Of course you could say that Bitcoin is worthless and not proved as store of value, but that's not for me or you to decide, it's what's decided by the market.
What exactly are the valid use cases that are not already better served with centralized systems THAT DOES NOT involve illegal activity?