This, of course, ignores another significant component of economic behavior regarding education. Specifically, in addition to it's vocational value, education is a service purchased to meet the human need for self-actualization. When you see a human-interest article in the local news about a 70 year old grandmother who has just completed her bachelor's degree, you are seeing evidence of economic demand for education that has no vocational basis.
I am not saying that the existing trend of the cost of tuition outpacing CPI can continue indefinitely. Clearly it can't. However, it is a mistake to label the present circumstance as a bubble.