Some points-
1. I laughed when the gentleman said that $3mm would be enough money for him. Anyone who says $3mm is enough will realize that whatever number they say is "enough" is not enough once they reach it.
2. Money doesn't make you happy. But if you're already happy and you have money, it can make you happier.
3. Money makes people pay more attention to you- especially people who didn't pay attention to you before. People will say, "well Barack Obama would never have shown up to your wedding before you sold your company for $1bb". Well no sh!t. Why would he? Charities will call you. "Well the University never paid attention to you back when you were poor". Universities and Charities are in the business of raising money from individuals.. Why would they? This will be tough for people without money to understand.
4. Those who have sold their companies find that money is sometimes harder to hold onto than it was to make in the first place. If you don't have enough money (to never work again), become complacent due to your original ability to make money (particularly those in tech world), you could find yourself broke.
5. Speaking of broke. Minimize your borrowing. The majority of very rich people who suddenly file for bankruptcy are over-leveraged and/or not diversified in their investments. An example: Let's say I have $20mm. I could go to a bank today and get a $40mm house. However, my taxes, upkeep, mortgage, and other lifestyle expenses would likely cause me to deplete my original 20mm within a few years.
6. When you're rich, its very difficult to deviate from an expected lifestyle. Once you spend 60k on a car, 90% of the time your next car will be more. This is true of houses and everything else you purchase. My advice is pace yourself.