Okay, since there aren't so many entries i felt bad to let only half win and the other not.
So i decided to give everyone a copy. Check your pm.
VanishedOne: 'I've no idea who they are, but it'll make a change from grinding local wildlife.'
Awolnation: "They are called the cult of the vault. I must fight them because they don't belong in this game. Also, finding all there symbols is a pain in the ass."
coxdr: "The Cult of steam must never thrive. Its goal is complete control of all things great in the world. They desire such things for they believe it will make them rich. I fight so that there is still some good in the world and will never resort to such vile practices... well except for regional pricing but I swear we had to do that..."
theslitherydeee: "If you do it you'll get the achievement Cult Following"
A very good reason.
Thespian*: "Is it not obvious? Because they're... well, you know... a Cult, after all. That can't be good!"
"... and besides the plot of the game requires from me to do so!"
You would have won too, but Coxdr already won one himself. :)