"we operate on a tiny fraction of the resources of any other top site."
Pardon me, but wouldn't that mean they need even less money? The way i see it you have costs for servers and bandwidth and the R&D of programming the site.. but after that, users basically fill in all the content for you.
Even having the 5th most popular website ever, with loads and loads of traffic, I don't see how hosting can cost more than.. say.. 500,000 a year.
Don't get me wrong I love Wikipedia, great idea, but I still think they ask way too much when they keep the plea-banners going until 20 million (for 2011 only? really?) 20 mill should keep you good for the next 10 years (i hope). I will be disappointed if i see the same banners this year, or next year.