Your reference to boys town missed the point. Boys town didn't run out of orphans to spend money on. They simply failed to spend a large amount of it on orphans.
A better charity to compare with Wikipedia would be the the Washington Monument Restoration Project.
See https://www.nps.gov/nr/travel/wash/dc72.htm
Once the Washington Monument is completely restored you can't spend any more money restoring the Washington Monument. If donations keep coming in, you shouldn't spend them on giving executives of the charity free ski vacations (yes, the WMF actually did that) You should instead build up an endowment that is eventually big enough that the interest covers all Washington Monument maintenance forever. Then and only then should you tell donors "look, we don't need any more money for restoring the Washington Monument. If you give us a donation we will use it for other things, starting with restoring the Lincoln Memorial".