I'm always shocked when people say that, what with books from Amazon and all the online reading, we don't need libraries. I remind them of all the people who don't have computers at home, or have had to cancel their internet service and really need the computer use the library provides (for free). And how the libraries provide so much more that they did when I was growing up, such as tutoring help, language help, job services, etc.
Easy: But the best way to really 'get it' is to visit your own local library. Do yourself a favor--go walk around your library, see how many folks are there and how they use the library; then check out a free DVD or music CD, or, of course, check out a current title. It's so much more fun than Amazon. Every visit helps the library keep its doors open, and after every visit one more person may become a supporter.