A good comparison of Wikipedia, since they are producing an educational product, is to compare them with modern universities, which are all "non-profit" as well. Look at many of the salaries at most colleges and universities, and you'll see many people making in excess of $100,000 per year, and athletic coaches that are paid in excess of $1,000,000 per year. Being classified as "non-profit" clearly does not mean that you have to pay your employees poorly.
And, of course, most universities also solicit funds and donations with the same agressiveness as Wikipedia as well. Got to keep that football and basketball program rolling, after all.