[citation][nom]robochump[/nom]I wonder how Bill Gates fortune is growing if he is a philanthropist? If that actually makes you money I want in!!![/citation]Charity organizations only have to give away 5% of their net worth per year to be considered a charitable foundation in the USA. Thus, if you can grow the foundation by 10% per year, you're still basically growing even after giving away 5%. That's not to say he isn't doing great work with the foundation, just that it can also be profitable.
As someone else stated, a diverse investment portfolio helps as well.
Gates would probably be worth double what he is today if he didn't give anything away.