Do you think you are in the majority, or the vast minority?

Congrats though, it must take a heck of a lot of willpower to keep using the darn thing.
It doesn't matter if he's in the majority or the minority, you still can't guarantee what group the OP would fall into.
Personally I quite like running on a treadmill once or twice a week and would probably use it more if I had somewhere convenient to put one at home. I regularly train outside as well, but even that gets a bit 'boring' as, like most people, I'm probably limited to a just a handful of convenient local routes.
I'm lucky that my local routes are a pretty good mix, but if you're running 3-4 times a week then it doesn't take long before your day-to-day runs become a bit mundane.
I love it when I get a good weekend and can go off running in the hills and exploring a new area, but there's no way I could do that regularly, as it'd just take up way too much time.
Inside or out, you need to either enjoy it, or to have a lot of willpower to stick with it.
For me, I try to push myself to keep fit using regular, quick and convenient training sessions (albeit quite boring) so that I can then go out on an occasional weekend and really just enjoy being out in the hills, whether that be running, walking or cycling.