I've been at a BMI of nearly 40 just a few years ago. Fast walking to the car like 100 ft away left me out of breath (which is when I decided I was going to lose weight that time). It certainly can be hard when you get to the point like that. And any attempt at doing so just makes you feel embarrassed to be in the state you are in without actually burning a useful amount of calories. Exercising certainly is not how I started - I just stopped eating as much and that's also unpleasant when you start and it takes time to get your body to eating less (and it pretends its starving in the meantime). Also, not everyone is my size nor does everyone enjoy pushing themselves to their cardio limit (or at least, they don't know what activities they enjoy enough to do that or they aren't able to regularly do that).

For me, exercise has had mixed results for me. Sometimes, I've used it to justify eating so much more that I probably put on weight. This was particularly true when I started doing long-distance bike rides (like 100km rides); I tended to mistake being tired as needing calories, so I'd overeat just because I needed rest or sleep - the goal wasn't to lose weight though, I just liked riding. When I combined it with intermittent fasting, its been pretty effective because I'm more limited by stomach space when eating all my calories for the day at once. So I couldn't really eat any more. But its not a method for everyone.

Also, there's a time commitment. I haven't biked in a while because I'm at work like 70+ hours a week during the summer. Probably unsurprisingly, I've put on a fair bit of weight this summer. The only way I've been able to get consistent exercises is being a NEET or via a commute. Guess when I first got a VR headset, there was a few months where I was probably averaging an hour or more per day of at least moderate intensity exercise (and eventually intense exercise as I got better). For people who have other commitments like children, I'd hope they'd get at least a fair for of exercise playing with them during their younger years, but eventually that goes away for many and there's still the time that you need to spend with them.