And it only says that 80% completed college. It doesn't say how many of the 20% started their college education. Many internet billionaires met in college and dropped out because they had a great idea (of course, most of the other drop outs probably didn't succeed, but that's another story).

Yes, the base rate of college graduation in the general population is a good bit below 80 percent.

Lets put it this way. The 20% lead, the 80% is a "no-brainer"