From what I've read it costs around $2 million dollars per year just for the servers to host wikipedia.org and then there's employees that need paid and office space that needs rented etc and if I recall correctly the article I read said it cost around $60 million dollars per year to keep wikipedia online with all the expenses.
And currently wikipedia has millions of dollars in the bank that exceed their operating costs so they're good to go for awhile on keeping wikipedia online whether they get donations or not.
If it were me though I would place ads on that website and make it a business and earn a good amount of money without asking for donations.