they only moved back because refunds started happening,
Kind of, but refunds only started happening because steam allowed it. And steam only allowed it because there was enough of a shitstom.
Negative reviews by themselves don't do much, you are right about that, but they do kinda show a community's mood (especially to other gamers in the community).
they had made their money already
Helldivers is a game that has a lot more monetizing potential than just the initial sales.
Or just oligarch or power addict. In the eyes of most people, wealth is about luxury, material goods and fancy toys. Of course that's part of it, but at a certain point, wealth is no longer about luxury and toys, it's about power and having control over resources everyone else depends on.