But if nobody wants our world and they're scared of intelligent life then just send out Von Neumann probes to ensure intelligence isn't showing up elsewhere. First mover's advantage nullifies the entire dark forest.
So either they'd - already have gotten here & already have destroyed the earth when we showed intelligence OR - already have gotten here & don't care about destroying intelligence.
Or... civilizations don't experience unbounded growth over millions of years across millions of light years to begin with.
Many motives from the age of exploration could apply - imperialism, religious beliefs, religious or political differences, cultural exchange, scientific discovery, competition with others, etc. People don't always take the cheapest option; the same could be true of aliens.
We were almost wiped out after the first large impact. The impact that happened a few millennia after we killed all those awful looking smarty octopus that lived in this planet. But we could not defend against the large Comet, it come from behind the Sun and way too fast. We had minutes notice.
Some microbes survived...And here we are again typing on our keyboards. :-)
Gur nyvraf ner ynathntr areqf. Gurl bpphcvrq Rnegu fb gung uhznaf jbhyq perngr n arj qvnyrpg bs gurve ynathntr.
It seems safe to say that there isn't life that wants our planet.