Having full ownership over your money in digital form has quite a lot of disadvantages, so many disadvantages that it makes it a bad idea to do it in general. However, there are a few advantages under certain circumstances. You can easily wire money-equivalent into a country where banks are closed. It also forces countries to be a bit more cautious with acute money regulations in times of crisis (because Bitcoin is a tool to circumvent those).

I do however agree with your post on general. Bitcoin (and all other crypto currencies) is used for money laundering, speculation, doing things that would be illegal with properly regulated assets and for buying illegal things like drugs.

It's been around for quite some time, if there were more use cases we would already know by now. There has also been no substantial development since Etherium "let's make it turing complete because what could go wrong lol" and the world pretty much agreed that it's a bad idea to couple money transfer logic to publicly available code while a bug can make you lose all your money connected to that logic.

It's not like it wouldn't be possible in general. But nobody cares and obviously nobody sees how serious development would lead to anything useful (very few counter-examples like the people that created Monero).