Yes, in some circumstances I absolutely agree, there's a lot of reasons someone wouldn't be motivated to do something, but my opinion is that the overwhelming factor is that they don't find it fun enough to try and overcome those things. Sure, someone might feel uncomfortable at a gym, but
often that's a matter of finding one that suits you, getting used to it, or finding it remotely fun for some reason. If you find running satisfying enough, the likelihood that there will be an insurmountable obstacle to doing that is usually low. Buying $400 shoes won't make you love running.
For me, I hate the cold more than I like snowboarding, and I don't really have the money to invest in equipment. If I loved snowboarding enough having had a very good experience initially, perhaps through one of those variables that you mentioned being tweaked, then I'd find a way to do it by sourcing used gear or w/e, but ultimately I just don't like it enough atm to do that. Therefore I'm very much in favor of tweaking anything to explore a new activity, but I'm doubtful that more than a tiny percentage of people stick with it for more than a month because they really wanted to play cancer-girl's song. It wasn't an innate drive to pursue an art, it was an external momentary source of novelty, akin to setting a New Years resolution.
Likewise with ice-skating or something. If you feel genuinely driven to do that, but you don't like skating indoors at the local rink, you'll try and do it regardless of your equipment, and try to find an outdoor rink, or maybe a frozen lake, or pond, or you'll be sad if you can't because you live somewhere too warm with a culture that doesn't support it, or you'll vacation to somewhere colder. I always recommend not trying to find something fun that you don't find fun, but instead just exploring many options horizontally to eventually find something you do find fun. Great, you don't like the gym, try climbing, try hiking, try swimming, try running, whatever. Then think about spending $$ as you see fit to support the thing you're actually compelled to do.