You're helping yourself. In fact, you even boost your chances for college. Well, take getting in. Every college application has a section on community service. When you have something to put in that space, it says you care enough to work with your community.
Colleges love that.
On the money angle, certain community service groups have scholarships that help you pay for your education. You start to learn more about the needs of the place where you live. In the long run, this is what it's all about.