They are usually not short on cash and can handle their own affairs.

Maybe, but this isn't their comparative advantage. They could spend some time becoming an expert on health, but it makes much more sense to have a health expert take care of the health stuff. I expect there are enough trivial inconveniences along the way that even academics with the money don't do this, and that seems very bad.

Or their partners/secretaries do that already.

I see no particular reason that the partner of an influential scientist ought to be particularly knowledgeable about health. And do academics even have personal secretaries anymore? I haven't observed any such people in my limited experience in academia so far.

I am also wondering whom you would name as top 5 or so "important scientists"?

Dunno. This is out of my domain.