$6MM invested with a 6% return provides a $360k pa lifestyle just living off the interest. That seems like quite enough for houses, spouses (well—maybe spouse; alimony could eat into that quite a bit), cars, and children.
Berkshire Hathaway is willing to guarantee you a $205,000 annual income from that sum in an annuity, which is not a bad deal at all, but it's not 'never worry about money again', it's just a really nice salary, and would be substantially depleted in the case of any inflation at all.
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.
You'd be 37 years older and making less than 1/4 of the income, adjusted for inflation.
BH annuity is not a bad deal, but losing 2% of your income a year will sound tolerable until about year 5... =)
If you retire mid-twenties on $5M, there's no way you'd make it through 70 on that, if you did nothing else active (read: risky) to increase your income.
Follow the thread UP, and you'll see it's the core of the conversation - as to whether one can live off of 6MM for the rest of your life. I call "ceasing working and living on the money you made previously" retirement, you can call it what you like.