Fair question. The profit incentive in this case is not meant as a psychological incentive, but a purely economic one.
If I make money doing something, I can keep doing it. If I don't, I lose money and so I can't.
It's a natural selection mechanism that will always happen. We broke it (aka we don't like it) because we moved from the consumer choosing who profits to central banks.
So, doctors that are not liked by the consumer don't disappear as fast as they should. They also don't land where they could do good because we leave everything to arbitrary judgements of well meaning bureaucrats instead of the choices of people that have to be served.
No system is perfect but we are missing something important in healthcare and I think this is the main culprit.