IMO "Because I just want one" is about the best reason to buy anything, firearm or otherwise.
9s are a blast to shoot. Barely any recoil, hold a million rounds in the magazines, lots of different kinds of ammo, cheap ammo, they'll work just fine for a self defense gun if you wish. Kind of the best of both worlds between a 22 and a 45.
Sgt Lumpy - n0eq