Ah. I had no idea that they ran out of orphans. If they did, then it would be a perfect analogy. Boys town takes care of all the orphans that it is their mission to take care of, keeps collecting donations and spending on other stuff. The Wikimedia Foundation does everything needed to put an encyclopedia -- the thing that it is their mission to take care of -- keeps collecting donations and spending on other stuff. Thanks for the great analogy, and I apologize for misunderstanding and assuming that there would always be plenty more orphans to take care of.

I am going to think about this, do some research, and see if I can turn it into an essay on Wikipedia about collecting money after the job is done. Thanks!

Didn't the march of dimes also keep taking in donations after polio was eradicated?

Full disclosure: I am the author of the Wikipedia essay "Wikipedia has cancer"