This is SOP for showbiz.He chose the profession,he reaped the rewards and the pitfalls.His wives were very probably gold diggers,like most showbiz wives.But he should have known that.
Sounds like he left the first one for the nanny, so I don't blame her for not sticking around.
The second one was with him for 20 years through numerous rounds of substance abuse, rehab, and relapses--crap that a whole lot of women wouldn't hang around for, especially if they could just get the money in the divorce anyway.
They don't sound like gold diggers.