You seem to be fortunate enough to have other options. Not everyone is so fortunate. Personally I believe society as a whole is better when we offer opportunities for education and self-improvement to those who can't otherwise afford it. Many people derive real value from public libraries simply because it is the only option they have for the services it offers.

Personally I haven't set foot in a library in a long time but I would proudly and gladly vote to increase funding for libraries, even at my own tax expense. I earn enough for my family to live comfortably. Increasing my material wealth further won't bring any increase in personal happiness so I will gladly spend it to better society as a whole, even if I do not directly benefit from it.