i started looking into gear as a magic pill, but the more i learned about gear, the more I learned about how to make gains without it. So I started making my first real gains not because of gear, but just by researching it!
with that said, I plan to do a sust cycle sometime in the near future and I guess it's cause i feel i'm too small/skinny. I think that's why everyone takes it, because they want size (assuming we're talking about bulking gear, not cutting gear). I think people WORKOUT to better their self confidense and most of the other things you listed, but they take steroids to increase their size, meaning they feel they're too small.
that's my 2 cents anwyays.