yes, funding is bloody hard but the steam engines and heritage railways seem to do fairly well, in fact fare much better than nostalgic aviation it seems.
That's probably because steam restorations are usually costed properly before they're started, there's honesty about what needs to be done and how long it will take, no-one uses hype and spin (quite the reverse) and no-one tries to make money or take large salaries out of it.
As with any charity, donors need to feel every penny is going to the cause, not to some schemer's wallet.