There is always some amount of money that is worth the trouble. Now, it may be some amount of money that cannot be paid by any entity aside from governments, Exxon, Apple, and a few others, but it is some amount of money nonetheless.
The client can agree to a ridiculous rate, but actually collecting is a whole different story. My gut says clients with red flags like this will be exceptionally difficult to collect from.
You could perhaps deal with it by insisting on being paid up front. But then I'd worry about the potential for lawsuits, if the client really is that crazy, and that's a potentially unlimited downside you can't work around with higher rates. The more he's able to pay you, the more he's able to pay his lawyers when he sues you.
Happiness isn't the only thing we care about. With enough money, I'd start thinking about optimizing the world, or at least give something to the most efficient charities out there.
With enough money, I would do the same. With too much money (say in the billion range) I think I would go all well-intentioned super villain on the world.
Hundreds of millions is two orders of magnitude more money than "the first few millions." To me that seems pretty significant. And even more so when you factor in how many more things (or even classes of things) you can buy with $10E8 vs. $10E6.
