Now and then when I talk to people about their careers, there seems to be a strange undercurrent of guilt when they discuss having their ideal career. They feel that what they truly want to do is useless, that it doesn't benefit people, or that they're being selfish. I usually encounter this among artists or people interested in video games, but I see it everywhere.
In short, I meet people who think "Doing what I really enjoy doesn't make the world a better place, so I shouldn't do it."
What they're really saying is "I should do something I hate and would be lousy at in order to attempt to make the world a better place." It's a strange kind of moral argument.