Every person are rich in one way, but poor in another. A person with much money, but is lonely, might be sadder then a poor man, that has good company. But a poor man, might struggle, just to stay afloat, while the rich man have no such worry.
If we spend life, thinking of what we don't have, we will always be depress. Every person is rich in one way and poor in another. Enjoy what you have, work for what you don't have. But if you don't get what you don't have. Well, as the Buddhist says, if it is meant to be your's it will be your's, if it is not your's forcing it won't help, so sometime you need to learn to let go.