Since there are supposed to be so many different ET species visiting earth [I've heard the number 57 used] why couldn't a galactic war be fought in and around our planet if there are already ET's in residence here? Rather like gangs invading another's turf to spread their own influence.

The old "Nordic vs. Greys vs. Reptilians vs. Insectoids" argument?

If their wars are anything like our own, then we'll be at the mercy of the victors, whoever -or whatever- they may be.