Yes, they get enough donations to cover their costs, just like Uber has enough VC cash and loans to continue its operations. It's non profit tax status is not strictly relevant to the fact that you typically need at least as much as money as it takes to run your entity rather than less. In my opinion, this doesn't change the spirit of the point that Wikipedia doesn't make money from its free, high-traffic service but rather from favorable financing for its goodwill and assets similar to a not profitable startup.