As the sibling comment points out, assuming Wikipedia's endowment sees 5% returns, it needs to be $54 million just to cover Wikipedia's hosting expenses. That doesn't cover any other Wikipedia/Wikimedia expenses like their full time staff or other OpEx.
If the endowment gets less than 5% returns it needs to be that much larger to cover expenses.
If the endowment gets less than 5% returns it needs to be that much larger to cover expenses.