The issue is that capital is power, it’s not just spending money. So the moment you stop using your money as capital to exercise power over others you stop being a capitalist.
The thing is though, nobody got wealthy without using that power, and that process is self-reinforcing. It’s a kind of addiction. By the time you’re a hundred millionaire you’re surrounded by flunkies whose paycheck depends on you sticking around and letting them wield your capital power on your behalf. They will strenuously advise you to keep your investments, and it’s hard to work against that pressure.
You are insulated from the day to day minutiae and the consequences of your decisions, and you have to justify in your own mind the decisions that got you here. To break out of that requires a profound crisis of conscience, but you’re extremely wealthy and you are insulated from any consequence that could possibly cause that crisis.