Actually, it's even worse then that. The concept, as with many conspiracies and occult is that the alien forces want to control and enslave humanity, not wipe them out.

It's even mentioned by the war planet commander how much better it would be if the earth was destroyed and everyone died, but the alien overlords want to use humanity as livestock and slaves. Continuing the cycle and feeding off humans and using them as currency... without their consent or knowledge.