So invoking power-of-attorney over someone isn't always the solution to their mental health. Its an extreme move, and I'm really not sure if its designed to be used in the typical mental-health case.
Its not like the mentally ill are suddenly incapable of performing useful work, or unable to watch over themselves. They just have... delusions, bad memory, swings of mood, terrible sleeping habits, etc. etc. They need help, not someone walking in and stealing their money / taking their house / losing all sense of agency all together.
Mental health is... difficult, but livable. Extreme actions like invoking power-of-attorney probably makes things worse in more situations IMO.
You may be thinking of Legal Guardianship. Power of attorney just means someone is authorized to make the same legal decisions as the subject of the power of attorney and can be overridden by the subject.
Brittany Spears was subject to and abused by Guardianship.
I'm not saying Brittney would have, just saying that it's easier to have a very public manic episode where your every thought is aired than it was 15 years ago.
There's a lot of stuff there, among other things:
> West said that he often has suicidal ideation. In a 2019 interview with David Letterman, West stated that he has bipolar disorder.