Thanks for the input from both of you guys. It's a little surprising to hear that 2-3 hours a day is what seems to be the general case, but I do think that I forgot that college has much more than pure tennis, what with classes and social life, etc.
You would think that a recent college graduate would have remembered that.
As for my friend, it's a mixed case. I would never say to his face that I doubt his abilities and/or his dream.
However, in all honesty, I heavily doubt his chances. He's 5 foot 10 with a serve that is average at best, has groundstrokes that need improvement, and his only upside is that he knows how to grind out points. I guess that he's physically in good shape (low body fat, good muscles, etc.), but I don't think that there's much chance that he's going to beat others who have been playing tennis at a far younger age and with much more intensity. Guess I just have to give him the benefit of doubt.