I like to think that quite a few of Magma and Aqua's members are less fanatical and more following their groups because their teams are the only ones who actually cared enough to take them in.
Seriously despite both groups having the most idiotic goals ever they do at least seem to actually CARE about their employees which is most than most teams or businesses in the pokemon universe can say.

I mean come on they get a break room, vending machines, breaks, and nap time and bed. I am pretty much sure an Aqua member mentioned having a dental plan. Out of all teams they are the less evil. With Galactic being the more stupid team (this was done on purpose, tough), but they come second