Remember to make that bias explicit, also in part for yourself: "Out of shape people who join a gym don't stick to high intensity training".

There is a huge difference between killing yourself over your lunch break/before dinner at home, and then taking a quick shower, and having to cut more than an hour out of your day because you need to drive to the gym, kill yourself for a very short period of time, then take several minutes to recover enough to feel you can safely drive home as a gross sweaty mess because you're far too uncomfortable showering around a bunch of strangers at the gym, and then do that multiple times a week. That's not just a commitment, that's a complete daily habit overhaul. Your life is now dominated by having to go to the gym.

Folks who decide "yes, I think I can spend 15 minutes a day, three days a week, on this" at home, with some expert advise from reputable fitness coaches who run also youtube channels, without any of the time investment, inconvenience, and complete upending of daily routines that comes with attending a gym, might have a different success rate (and we'll never hear from them. If they keep it up, they just get in a bit better shape and move on with their lives).