a) nostalgia and satisfying childhood dreams... (read: probable mid-life crisis)...
b) burned out on my last hobby, and really needed a new one...
c) a desire to deal with something mechanical for a change, rather than electronic black boxes...
i loved pinball as a kid, and can vividly remember thinking that it would be the coolest thing in the world to have machines of my own... now that i do, i was right, it IS pretty damn cool...