No need to go zero risk when the investment starts in your 20s. But of course, yes, inflation. But of course, you can draw from principal as well—that's how retirement funds usually work.

I'll put it another way: Maybe it's not 'never worry about money again'—people are prone to worrying, after all—but $6MM is more than the lifetime earnings of the vast majority of Americans.

If you can't make it on more than what nearly everyone else will ever see in their entire lives, that's your problem.