There are some fields where what really matters is talent and practical experience, not book learning. A lot of the best techies I know either have no degree or have it in something unrelated. The same is true of entrepreneurs and musicians, and probably other fields.
Consider also the absurdly rising cost of education:
"Median household income has grown by a factor of 6.5 in the past 40 years, but the cost of attending a state college has increased by a factor of 15 for in-state students and 24 for out-of-state students. The cost of attending a private college has increased by a factor of more than 13." -- http://www.economist.com/node/16960438
It's simple economics that if the cost of a good keeps increasing, it eventually won't be worth it for some purposes. It's not crazy to ask whether for certain people it's really worth it now. If your aim is entrepreneurship, you might be better off spending $150k and 4 years on starting businesses and learning on your own rather than giving that to Harvard.
Also, um, not everyone is due to be an entrepreneur. Outside of the Twitter Bootstrap startup world, the entrepreneurs need well-educated professionals to do the work, and will pay for talent.