Actually, it's very simple...
Most college professors have never been outside of the academic world, so it's easy to assume that the "theoretical world" they inhabit is the "real world."
Let's not forget that Michael Dell and the guy who started Federal Express were both told by their professors that they'd be failures.
This is also why socialism is so popular in academia! Just because it doesn't work in the real world shouldn't keep it from being supported!
Mark