I won't address your 80% figure, but college is like anything else. You get out of it what you put into it. A few people seem to think that their job is just to show up (often late) and wait for someone to unscrew their heads and pour knowledge into them. There are other people who spend their lives learning, both in and out of school. College was good for me.
College was useless for me. Have a very good sales job. Never once has anyone asked me about a degree.