Surely there is a stat that shows how many of jail broken devices have installous. I would wager that it is easily over half.
I'd be willing to contribute to the same bet. Anyone who thinks the majority of jailbreakers do it for customization is
likely mistaken. Customization gets old. Downloading new apps all the time for free doesn't. Not saying it is right to do so, just that it is/was the main selling point to jailbreaking.
You don't have to look far to see that jailbreaking = piracy for most people. No jailbreak since iOS 6 (which has been a terribly long time in e-years) equals no more Hackulous community.
I think most people, however, have seen that it just isn't practical to steal apps, even if it is easy to do so. There are only a handful of quality apps that any one individual can enjoy over a certain span of time anyway, so it isn't that expensive.