This is quite different in CS programs though. Where (a) there are few post-docs. (b) grad school is a great place to connect with bright hard working CS stud

This is quite different in CS programs though. Where (a) there are few post-docs. (b) grad school is a great place to connect with bright hard working CS students. It's a place where a lot of great ideas and companies come from. In some ways its a "low risk" incubator. You get paid to attend, and a stipend, in most cases. A lot of research ends up being the basis for a startup company. And if it doesn't you get a PhD, which is still very marketable. The downside of doing a PhD in CS, especially at a top 20 program, is really just the possibility that you may have hit it big in the 4-6 years you were getting your PhD. But of course you have to factor in the fact that being in grad schools opens new doors to hitting it big. Plus, at least for me, the college life is just fun, and something somewhat hard to replicate a few years out of college.