In many instances, university professors aren't putting in a 40-hour week for the university - they teach two or three classes a week, keep some office hours, and spend the rest of their time getting published or doing research (which pays above and beyond their university salary).
I follow you up to your last clause, and then you lose me. The rest of our time is indeed spent doing research and getting published, but I think only in exceptional circumstances does that pay more than a university salary. Publications fall under the category of "professional development," one of the three categories on which we are evaluated each year as part of our job.
With this sort of misconception, it's no wonder that you chose a university professor as your dream job--I hate to be the one to burst your bubble!