This is a cynical observation, but it's true. For example, my wife and I contribute to a nonprofit group that has the most disorganized development operation one could imagine. Nearly 1,000 people attend this breakfast, most of whom have never given money other than to buy breakfast tickets. But each year we're shut out. This is not an egregious example of donor abuse, but it's not uncommon.
Donors have countless reasons for giving.
Some want recognition and social acceptance. Others give out of guilt or because it makes them feel good. Art patrons give because they enjoy the culture provided by the opera, symphony or museum. Experts can provide an abundance of other motivations, but what it boils down to is that these donors all share the desire to receive a psychic reward. But donors will only support so many worthwhile causes.