That's a very good point. Doctors and Lawyers, to take your example, are obviously intelligent and by definition successful people. Yet their success is capped, there is a ceiling in these careers - a lawyer can never really change the world affecting literally millions of people. Sure he can work on an important case, and sometimes the law can change as a result of important cases (well not so much the law, but the interpretation of it) but he/she will never make a world-shattering breakthrough, a product used by hundreds of millions of people, in the way that a software engineer can.