I agree with this except just to point out > Because that's the point at which you have enough wealth to live a comfortably middle class lifestyle for the rest

I agree with this except just to point out > Because that's the point at which you have enough wealth to live a comfortably middle class lifestyle for the rest of your life 15M is far from middle class by any measure. 15M affords you a big city place, a place for winter holidays, and a place for summer holidays. With still left to have spoiled little kids (and possibly spoiled grand children). Also, 15M is not static money. If you have that much money you will certainly gain an income from just having that much money.