Well for one they get a community in general - friends, neighbors, acquaintances, firefighters, volunteer snow plow operators. Everyone gets some help here and there, like when you're stranded and a stranger gives you a ride or when you're a few cents short and someone picks up the tab. And some people have had to rely on soup kitchens and shelters themselves, so they give back by donating or volunteering with them when they can. You give back to the community because the community gave to you. The man you forgot about who helped jump-start your car years ago may be in need of a meal at the soup kitchen, or the old lady who called the police when she saw you getting mugged may have been hospitalized and lonely in need of company, or unbeknownst to you the son of a firefighter who died for the town is able to go to school because he received a scholarship through a charity that you donate to. It's the sum of all these things that you may never be able to pay people back for directly, so you help who you can within the community, and in turn you hope they will help someone else and cycle it back either to you or someone who helped you.