Ive found the helicopter method profitable in the past. You just need to cherry pick out the people who wreck/Crash on the road. Don't go to cartels/Red-zones. if you fly over something and you see hostiles with a gun simply don't land. When i first started on asylum i came up to a wreck of 4 rebels fully geared and revived them and got 50k as a thank you.
Can't afford a helicopter? Go to Athira, Smaller city less medic's and people still constantly die there. Just make sure the shooting stops and clean up afterwards, not that you even have to wait for the shooting to stop. Medics risk absolutely nothing if they are on foot, if you die as a medic it means nothing as you don't lose money for dieing.
Finally the most important note. Medic is not a slot that is intended to make money. It is intended as a slot to role-play a different role. Attempting to be a "Career Medic" will not net you any money but it wont really lose you any money either as again if your on foot you have zero risk.
That being said i do think medics need some help but plenty of suggestions have been suggested before.