What are you basing this assertion on? It was closed because of the pandemic. When that was over Allen had been dead for several years, his instructions had been to sell everything and give it to charity so that's what his sister has been doing. No one attempted to reopen with alternative benefactors or see if visitors would come.
I was there right before the pandemic and there were a decent number of visitors (given that it was a weekday afternoon).
But the fact is that most museums rely, in least in part, on grants and benefactors in addition to visitors.