Well, I don’t have the definitive answer to this question, but I have a belief about it that im sure others here share.. It isnt meant for everyone, but i think the vast majority of people it will work for. If you want to find true happiness, you have come to peace with what you have. Most people are always fighting to make their life perfect. They work hard for a pay raise, or to get into a better college, or move to a bigger house; buy a better videogame that will finally satisfy them.
Except there is a basic flaw in this goal, humans adjust to their surroundings. They get used to them. They become normal. If you are held in a prison for 30 years and tortured daily, after awhile you will get used to it. Now, at such an extreme as that, it aint ever going to just be day to day life, but you will get more used to it than you think would be possible. Same goes for bill gates.
There are billions of people who are currently starving or on the verge of starvation, working their asses off so they don’t starve. If they aren’t starving they are probably pretty fucking happy. Now, you could say that they are just happy because they are ignorant to what they could have. Well, true, maybe. But then again, so are you and i, and even bill gates. Bill Gates isn’t immune to disease, or stress or his ass itching. he cant fly into space without a space ship and suit. one day it will be possible, with implants if we are around for much longer.
So, yes, bill gates' problems sound mighty minuscule in comparison to yours. But he gets used to them, just like you don’t worry about starving to death or getting shot everyday, (most likely, maybe if you’re in Iraq or Afghanistan, etc).
So the point is, no matter what you have, you will soon get used to it and it will seem normal, and soon you’ll "need" more. Video game Graphics is a good example. If you could play games that were made ten years from now, you would be blown away, but people from twenty years in the future would be bored to death.
I would encourage everyone to live homeless, or in the wilderness without any modern convince for at least 6 months straight. Of course that wont happen, but if it did, I think a lot of people would stop worrying about fashion, what kind of car they drive, their job, etc.