Thushan, but what I have to question is that so many other professions have the power to make a difference to people as well.
Engineers - they design houses, roads, sewages, electricity lines, cities, buildings, cars, medical equipment, basically just everything you see around you that helps improve your quality of life. The keyboard you're using now, the computer you're using, the LCD screen, the table it sits on, the chair you're sitting on and the house you're living under were all once feats of engineering and in many ways, even the medical field owes much to the feats of engineering. I could argue that engineers make a VERY big difference to the lives of people. Imagine if an engineer could design a good and efficient water distribution system which can be installed in a country suffering from poverty.
Teachers - they are the ones who, in some way or another, determine the future of our race - they teach the young ones not only academics but values, life skills and experiences. Without teachers, many students will fail to learn effectively and we all know that at some point in our lives, we have met a teacher who has inspired us in some way or another.
Nurses - they help patients just as much as doctors do
Scientists - they are the basis for the majority of our advances...etc.
Lawyers - without lawyers who work for reasonable prices defending those who are victimised, what would happen in society?
OK, I'm getting tired, but you get the point, doctors aren't the only ones who "help people" despite what people seem to think.