> There's a bias here, but its not about how common the disease is, but who it affects and how.

This worldview requires believing that doctors dgaf about their family members.

Most doctors who do this type of medicine wouldn't work with family members. Not many fathers, uncles would work on their kids, nieces or mothers and not many mothers either. You would go to a different doctor if possible.

"They don't care because it's doesn't affect them personally" requires "they don't care about other people".

My general impression from half recalling whatever stories about new medical discoveries, is that the motivation is more often a problem that a family member of the researcher has rather than a problem that the researcher personally has.

I really regret using "common" here, because the issue with endometriosis is the complexity of the disease, lack of understanding, and lack of clinical management tools. Not the rarity.