Retirement accounts mean different things in different countries. In some places you are forced by the government to have one and you only can only start withdrawing at a certain age. In places like the US, they are optional but you get certain tax benefits and protection from bankruptcy or divorce courts, among other things. Sometimes you get employer matching for every dollar you contribute to an account, such as in a 401k account.

I actively self-manage my IRA accounts and am doing pretty well, so I don't see the need for cashing out everything and going to BTC.

However, there is always talk about the possibility of the US government confiscating retirement accounts to pay down their debts, just like what they did with Social Security. It is not something that they can easily do as they need to pass a lot of unpopular legislation, but it is something you should watch out for.