Skewed giving reflects nothing sinister about society or human nature. It stems from the laws of arithmetic. Neither income nor education strongly correlates with high percentage giving. Belief in an afterlife and biblical literalism do correlate. The one top factor, washing all the others out, is attendance at worship.
Money follows feet.
If you want generous contributors, you need to show them that your institution's work is helping them. The Encyclopedia Britannica is in trouble. Sales have fallen by more than half since 1990, with no end in sight. Britannica ignored the coming of the information revolution and fell quickly from the top of its field. Congregations are in the information business.