The problem is not that those problems are less profitable. The problem is a combination of
1. Those problems are much harder
2. The potential harm from getting them wrong is much larger
Yup, I definitely agree that they're harder (and noted this). But I'm not sure I agree with your second point. Or rather, I think there's some nuance to it.
Sure, using AI to treat people without a human in the loop would clearly do harm. But using AI as an assistant, to help a doctor make the right diagnosis, seems like it'd do the opposite. It'd help doctors serve a larger patient population, make less mistakes, and probably equate to less harm in the long run.
Anyway, I think we can all agree that using AI for anything other than ad targeting is a net win.