I have to agree: The only person who'll get hurt if you quit the team is you.
You might get more sympathy if you give us some examples of what these guys have done that is so disrespectful. And ditto for your coach: What is he doing that's wrong? If he's not having you run enough, why can't you just run on your own, as was suggested above?
In the meantime, have you talked to any adults around you about your situation? People who know you are likely to give more useful advice than a bunch of know-it-alls on an LRC message board.
Even if none of this is your fault, and these guys really are a bunch of immature idiots, so what? This not the last time you will have to work with a bunch of immature idiots with no adult around to make them behave. In situations like that, your best choice is often to suck it up and be the adult. It's usually unfair, and it's always a pain in the neck. But learning how to get along with jerks is a valuable skill. If you get good enough at it, you will eventually get paid a lot for it.
PS What happened to, "Whatever does not kill us, makes us stronger" or "When the going gets tough, the tough get going"?