If I'm honest, a lot of "do gooder" professions actually pay good wages. Doctors are one, definitely. But social workers are relatively well paid, as are police officers, counsellors, teachers, and so on. Nurses and para-medics are hardly scraping by, either. I think 50% of the attraction is the good money and job security, then the other 50% is the 'feel good factor' of helping others for a living.

When I was in primary school all those years ago my Deputy Head Teacher actually told us bluntly that if she wasn't getting paid okay for her job, she wouldn't do it. I forget the exact topic which made her say that, but it's true. There is money involved in the motivation, definitely.