I'm a bit mixed on this matter. It's yet again an example of how these institutions decide for you what you can do and what not, but on the other hand it will somewhat prevent mentally challenged people from harming themselves.
Prevent from harming? What are you talking about? Would you like someone to follow you in every step, telling you what you are supposed to do and stopping you from doing dangerous things? Don't drive fast! Don't do extreme sports! Don't buy cryptocurrency! At some point it's fair to ask if we're adults or not? Being of age used to mean that you're able to decide for yourself and don't need mommy and daddy anymore.
I think a person should decide how to manage money.
And you are right to think that. Personal property used to be sacred and protected by the law.