[Lemmy]

Seriously though, I think that any aliens that visit Earth would probably be friendly - any race developed enough to have interstellar travel would probably not be warlike, or they would have destroyed themselves sooner. On the other hand, we're on the verge of achieving spaceflight, and we're pretty warlike...

they wouldn't have to be warlike throughout their entire development, maybe they had time of good leadership and lots of wealth, so that any war can be avoided, then the economy collapses, leader is assasinated, big alien empire on the verge of civil war, evil alien people with big evil mojo weapons come to earth, and think conquering earth and a new batch of slaves will boost their economy