The average doctor in the U.S. makes $350k a year. Why?

If you study medicine, you will spend +10 years trying to get to that position, and after that you are set.

If you study other subjects such as engineering, you may spend +10 years to get the top qualifications (undergrad, masters and PhD is 10 years, many will do postdocs as well) and still will spend your lifetime chasing jobs, constantly reinventing yourself, and most people will never make as much as a medical specialist consistently.

Healthcare in US is lucrative.

We could trivially fix the "80 hour weeks" piece by increasing the number of places available in medical schools and residencies, but the AMA intentionally keeps that number small to maintain the status quo of intern hazing and high salaries.

It takes similar effort and abilities to get a STEM phD, but the researchers working on drug discovery or mitigating the climate crisis or whatever other socially-beneficial thing make 1/3rd what an MD makes. The power of the AMA in guiding the entire healthcare system to the benefit of MDs shouldn't be underestimated.