My understanding is that academia is very competitive, so I don't understand how you are only going to work 9 hours a week. Further, you'll probably have classe

My understanding is that academia is very competitive, so I don't understand how you are only going to work 9 hours a week. Further, you'll probably have classes to teach which surely take up more than 9 hours a week. Also, since tenure is largely tied to the quality of your output, you can't always work on what interests you--you have to work on what you can publish.