I'm not sure, I often ask myself how I ended up in those situations as well (I'm a coder FWIW) and I still ask many designers working on projects such as these

I'm not sure, I often ask myself how I ended up in those situations as well (I'm a coder FWIW) and I still ask many designers working on projects such as these why they're doing it. The simplest answer seems to be that it just seems like the most natural place/industry for designers to gravitate to, and once they're there, they're kind of stuck in a tunnel. Coders have it a bit easier in that the path to starting their own thing or hopping between industries is much much shorter and easier. BTW I don't think you're being naive at all, I think these are very good questions to ask.