I think it was an estimate by Saurik that 7-10% of unique iDevices installed cydia at one point or another, and I bet many of these are not hardcore jailbreak fans.
Right. Like I am a jailbreaker, and have helped a few friends jb their iDevices over the years. But I only count myself as one out of four or so Cydia installs that are hanging by a thread for the latest jailbreak release to tweak my new phone. And I bought an iPhone 5, so Apple has my money already!