People doing amazingly well or, who have done amazingly well have a huge amount to lose. I suspect a lot of people who go are at a tipping point, or maybe on their way down.
Plus, if they've reached the pinnacle of where they hoped to get to- and they still feel unsatisfied- where else is there to aim?
I think it can also be really lonely. There are probably an awful lot of insincere people around them for the money and fame. Money really changes how people respond to you.
It's got to be such a weird life to not be able to go places without being recognised. I don't think they have the same freedom 'normal' people do. They're always 'on show'. If they're having a bad day and snap at someone, they could get cancelled tomorrow.
If they've grown used to money and success, it may not be so gratifying too.
Plus, something like depression, bipolar, PTSD doesn't give a shit how famous or successful you are. It may even feel more important to disguise all that.
I do wonder, but you never know what's going on in someone else's head. There's a lot of pressure for those types of people, for example.
I often wonder why people I admire do it - for example, Robin Williams. He was a great guy who was nothing but fun. However, he clearly had a lot of inner demons.
It was discovered Robin Williams had Lewy Body Dementia after his suicide. It comes with some very distressing symtoms which must have been all the more distressing for not really knowing what was causing them and, how bad things would get. I imagine for such a brilliant mind to suddenly be struggling must be very distressing.
Some people in my family have suffered strokes which I imagine cause some similar symptoms- difficulties in remembering words and communicating. I think it's all the worse for someone who prior to it had a very sharp mind. They are all too aware of what they've lost and may never recover. It's so cruel the things that can happen to us.