Just as a supplement to @abelenky's good answer, there are some things to be taken into account that haven't yet been mentioned.
First, if you've been flying with a tailwind for 3.0 hours and the winds would be roughly the same, it's going to take you more than 3.0 hours to fly back along the same route, possibly a lot more than 3 hours.
Second, technically you can't just reverse course without getting a clearance to do so. You have to contact ATC and negotiate the course reversal. That could take several minutes, possibly a lot more depending on communications. The captain could, of course, decide to reverse immediately and negotiate the clearance later, but he would be risking a possibly dangerous reduction in separation from other traffic, and I doubt whatever the governing authority was would take kindly to risking a couple of plane loads of people for the sake of one individual.
Then, there can be special circumstances. For example, if you were flying Indonesian Muslim pilgrims to Mecca on a Hajj charter. I can't speak to current policy as I retired in 1999, but back then the practice was that once you were in the air, you did not turn back or divert for medical emergencies. There was always a doctor on board, and technically he could request a captain to divert to the nearest suitable, but in practice that was never done. It was expected that there would be occasional deaths, and we carried body bags for that contingency.