Yah, I'm gonna agree with fluffy on this one ... He's not trying to buy a P1, and if he really has that kind of cash flow, enjoy life a little.
There's a point where you get to "how much is enough" .. could he turn 4M into a life long never work situation again? Sure, if he's smart with his investments, diversifies his portfolio, and maybe has a few good/lucky ventures but none of that means anything if you didn't enjoy it along the way. Buying an MP4, or any 200-300k car isn't going to change his life financially in a manner that matters.
Happiness is important, because you sure as sh** can't take the money with you when you die ... come up with a financial model you are comfortable with, and live by it .. for me that model has always been 70/30. I try to invest/reinvest/save 30% of any income I make that will end up with my wife/kids/family when I pass, and I never buy anything that exceeds 70% of my yearly income over a 3 year period, with the exception of my home because California is expensive 
As an example, if I made $100k a year, 70% over 3 years is $210k, that's the rough ballpark of my limit for a car I would buy. If for some reason I finance part of it, I won't make another purchase of that size until the first one is paid off. I never have a asset/investment debt that exceeds that amount in situations where I don't pay cash for it outright, and I'm always super aggressive on finding the best interest rates possible if I do finance a purchase. (To be clear, I would never have credit card or revolving debt. Cars, real estate, etc are assets and can be sold to recoupe money if needed).
Keep in mind this model is assuming you are starting at $0. Starting with $4M is a different ball game, and you can do wonders with that money if you are smart about it, but it doesn't mean you can't enjoy having it too.
I'm not a multi-millionaire (per say), but I've followed this principle since I was 18 and I own several real estate properties and several vehicles following this basic principle, and I have no financial complaints, and no debt outside of my mortgage living on my moderate salary in todays market. I haven't missed a beat on enjoying every bit of my time, vacations, and material items along the way, including a handful of notable super cars
Enjoy it, and remember you always have to do what's right for you...
