Money money money...
"We never run ads on Wikipedia. Wikipedia is funded by more than a million donors, who give an average donation of less than 30 dollars."
That's $30 million. I have read estimates of their annual expenses (the links to which I can not find right now) which put those annual expenses in the $2 million dollar range. The story of what happens to the money and where it goes is interesting and needs to better known and publicized.