Professors spend months every year not working
I don't think you understand what professors do. They pretty much work year round, and when they get sabbatical, they use it to research and collaborate at other universities. However, a professor's job responsibilities go far beyond teaching, which is what most people assume is all they do. As others have stated, they aren't K-12 teachers who only teach.
aren't revenue generators
They're all revenue generators. Whether it be having a good program ranking and getting people to want to spend $10-30k a year at Ohio State, plus two forced years of room and board, or generating grants (in some departments), they're generating money. My department wasn't huge in grants like natural sciences and engineering, but my adviser had 2 continuous grants from the NSF, which is why they pay him "ridiculously" to be there.
If you don't like it, don't go to any university, and see how most businesses look at you.