Dude, don't listen to them. You'll find a whole bunch of jerks and insecure people at law school. I think it's great you're thinking so far ahead.
It's a tough decision trying to decide whether to go out of state for law school. But first decide if you truly want to stay where you are now. If so, you don't need to go to a top school to get a DA's job. They really care most about conviction (no pun intended).
Go ask them if they hire from the school(s) in your area. If so, and you want to stay, then you should simply go to school there. The best "in" to a DA's job is through summer 1L and 2L internships. Likely they hire right out of those, but go ask them to be sure before making a final decision.