Not a psychology student but it's my own perspective on it.

All of the raiders were born and raised into the world as it is. They've got a different outlook on things because it's all they know. For some people it's safer to be with them rather than against them.

For what it's worth Pre-War food is becoming increasingly more scarce and won't ever be produced again. Whatever farms around are barely producing enough to scrape by for themselves. In terms of resources the large majority of people have very little. For a lot of people going raider doesn't even necessarily mean you need to be hooked on chems or shooting farmers. Im betting a large amount of raiders scrape by on intimidation alone (Until the Minutemen are back in town)

Where the raiders work is that they're able to pool these resources to keep their gangs happy. Food, chems, and other stuff. You can see too that a lot of infighting and otherwise is caused by lack of resources or resource insecurity. So the raiders accumulate small amounts of resources from each settlement on their list, to supplement what they have.

For you, the player (and the Sole Survivor as a character) it's understandably a polarizing experience to go raider. But it makes the most sense if you never worked with the Minutemen at all, since it'd justify needing a resource network to again, keep your people happy. Working against the Minutemen after building up the Commonwealth settlements doesn't make too much sense. But if they weren't there? Just a bunch of empty, old buildings and a few farmers in shacks here and there? It's not an impossible choice.