Rich people are rich because they are smarter than the average person, inherited a lot of money from their parents who were smarter than the average person, or won the lottery.
Rich people often donate to charity because when they do, they're taxes get reduced (this is true!)
Of course some will donate because they care about the cause 
It's hard to define rich, because every person has a different opinion of what makes someone rich.
ex:
1) A kid grows up in the ghetto, the kid who lives in the middle class suburban neighborhood will be considered rich to the kid who lives in the ghetto.
2) A kid grew up in the suburban neighborhood, with parents who work average jobs, who can't afford to pay for college for their kid, or apt./dorm rent (for the kid if they must move out for school), or give them money monthly to shop etc., which forces the kid to get a part time job and take out loans.
A kid who grew up in the same suburban neighborhood, with a bigger house, parents have better jobs, they can afford to pay many things for the kids............but to be able to afford all these things the dad has to continue working till he's 65 to put the kid through school (this will still be considered rich to the other suburban kid who doesn't get all that)
3) Then you have the third which is MY definition of truly rich. The kid that grows up in a mansion, who doesn't have to worry about working a day in their life (because they will get an inheritance), who got a bmw at 16, who gets a shopping allowance of god knows what / month...
This will be considered to rich to the other suburban kid who gets close to the same amount of things, but won't get an inheritance and still have to worry about their futur.
Anyway no matter how you define RICH there is always someone RICHER than you..............