So in summary Wikipedia is a responsibly run nonprofit that spends slightly less than it takes in while providing a valuable service to millions (or billions) of users?
The summary is that the Wikimedia Foundation asks for and spends increasingly large amounts of money in donations mostly on things that are unrelated to Wikipedia. The writer seems to want the Foundation to use the money instead to build up an endowment (like universities do) so that Wikipedia is not eternally reliant on donations to survive. He also suggests that Wikipedia itself is fairly well-run, but the Foundation is not.