As a teacher of CS I'm very aware of this. Year after year, for the last 15 years the CS program has been the largest program where I work because the job prospects have been the best. But you can tell, in a class of 100 there are only 1-2 students who are in it for the love of material. The other 98-99% are in it for the job after college. Which is fine and expected.

But as soon as the paycheck dried up, those 98% were out and don't even care about the field. The 1-2% stick around no matter what.