No I do not like working with people. I would aim for surgery or radiology for this reason.
While the stereotypical surgeon may be gruff/demanding/efficient/decisive, most surgeons are required to work in and even lead teams. The profession selects for aggressiveness and confidence, not for loners (though there are obviously some in any profession). Medical training prior to specialization will be exceptionally challenging if you dislike working with people.
Pathology might be a medical specialty where you were able to indulge your love of biology while working in relative solitude, but that's a pretty narrow slice of the pie to target. Per your concerns about ROI, radiology is probably the medical specialty in the US most likely to deflate in the next several years, given that wages are exceptionally high and that there are few material barriers preventing radiographs from being read by physicians in other time zones, or even other countries.
A friend of mine who may want to Earn to Give for the purposes of effective altruism mused 'The wages of American doctors seem inflated right now. I wonder if it is likely that the American health care system will be fixed by the time I am able to work there. If I do go to med school that is.'
Right now, he is an undergraduate student from, and living in, Canada. He is about half-way through a degree in computer science, but he is taking some biology electives. There is a good chance he will switch his major completely to biology, because he no longer believes he wants to become a programmer, and because he is very passionate biology and the study of life, and he would rather go into grad school for biology, or maybe medical school. If he already completed several credits from a previous major, and by December will have done 2 semesters worth of biology classes, I expect it will take him at least another 3 semesters to complete his degree, and/or complete the prerequisites for medical school. If he gets into medical school 2 years from now, it will take him another 4 years of medical-school+residency to be able to practice in the United States, and 2-3 years more than that if he specializes, or goes to a medical school in the Caribbean (where getting into them is apparently easier than mainland medical schools, but to complete the training takes six years). So, it would be at least 6-8 years from now before he is a practicing doctor in the United States.
So, does anyone have any ideas of how to go about the solving the initial problem? What is the likelihood that the wages of American doctors will deflate in the next 6-8 years due to major shifts in how the American medical system is run? What sorts of changes ought one be looking for to answer this question: political, bureaucratic, technological, or cultural change?
edit: my friend in question has expressed interest in this thread, so if you want to make recommendations about or discuss medical schools in the United States vs. other places, or in general, or about entering the medical profession vs.s other jobs, go ahead. Such valuable information would be appreciated. I don't yet know if he himself will participate in this discussion.