Allen had a net worth of something like $20 billion. That’s enough money to fund the museum for the next 5,000 years. Maintaining a project like this is NOT expensive.
It's not about how much money he (or his widow) has, it's about no one likes to randomly pour money into something they have zero interest in, and we're talking about money perhaps in millions per year. And the administrative headache.
Exactly. Money isn't enough to keep things running in perpetuity or even for a long time -- ultimately everything has to be administered by an organization that has a self-interest in sustaining itself with a board etc.
If money is simply set aside to fund something, somebody still has to hire somebody to manage the thing, and oversee their performance, and fire the manager if they underperform, and find a new manager, and sign off on big decisions like a change of space, and so forth. But if that trustee just... doesn't care to do that... then what exactly are you going to do? Somebody would have to sue to enforce that overseeing, but frequently nobody cares to sue or has standing.
Seems like the bills are still being paid, though. The museum is still physically there, and someone (Vulcan) is keeping the vintage computers maintained and operational.
Implement ticket sales, events, fundraising? Get a donation from Gates? Buy the land or move somewhere cheaper. Invest in some solar panels and skylights?