Why would you want to join a hackerspace?
This is a very good question! And you can find your answers here:
http://lifehacker.com/5912598/how-to-find-and-get-involved-with-a-hackerspace-in-your-community
Take a few minutes and watch Adam Savage explain the reasons he likes to tinker and build and make. Lots of good stories that help explain the maker ethos.