When you get barely rich, like single digit millions, the banks will start to offer you "family office" services. They basically just take care of everything for you. You send them all your money and all your debts (even your phone bills and stuff), and they promise to make sure there is more at the end of the year than the start. They invest for you, they do accounting and file taxes for you. You give them limited power of attorney so you don't even see the tax forms.
If you ask how it all works, they tell you it's really complicated and you should just focus on doing whatever it is that made you rich and let them worry about managing the money for you. Sometimes they do ethical stuff, sometimes not, depending on which bank and which consultant you hire.
I'm not excusing the people who are here, just explaining how some people who you thought were good people end up in these leaks.