To those who've quit: What would make you come back?

I like bosses that are impossibly hard. If they aren't, they don't feel like a boss to me. Unless the success rate for the run is under 10%, it's not really a boss, in my eyes. I remember a Zakum run I was in that took about 4:30, that was really fun, and only 3 people out of the 30 that went in survived. Sure, now we have wheels and resurrect and stuff, so that would not happen in current MS, but it was still really fun.