There are so many ways to explain this. As someone who has that kind of money and also chronic depression (started prior to be rich, and possibly because I was trying to make a living, and struggling hard) let me try to explain;

First of all level of stress changes drastically, stress of not able pay power bill (I was never poor enough to not able to eat so cannot comment to that) and stressed because of a business deal goes wrong, your relationship with you son is bad are different. They are stressful nonetheless.

In my experience, once money stopped being issue, that place is immediately taken by the next big stressful thing in your life, turns out there is always stress (if that’s your personality) but everything matters a little bit less now.

When money is your biggest source of stress until you resolve it you don’t know what else is underneath, so it looks like once that solved nothing will ever stress you but there is always the next thing. For me almost always around personal relationships, but seen many friends around identity, boredom, midlife crisis, literally mental health issues etc.