Amazing. All those galaxies and Earth is the only one with life.
They can also clone themselves mining the resources and energy available at anywhere they land.
Such machines can colonize the space.
The second, a pathogen, is just as unlikely to get every last one of us. A virus with a 100% kill rate is highly unlikely. Look at Ebola, while weaponized Ebola would get a great deal of us it's kill rate is somewhere in the 90%'tile, I don't know the exact number but I know it is high and I believe that it is the highest. 10% of the earth population is still allot of people. Even if it is less than that, somewhere their will be a group of people that for whatever reason are resistant to the pathogen.
The only thing that I think is a real threat to our existence today, is a big piece of something floating around out there, deciding to slam into us down here. I don't think we have the capability to do it to ourselves. I heard someone say that it is likely that we will keep resetting ourselves back to the stone-age at a certain mark in technological progress, which I think is a little more feasible, but I personally believe that mans desire to cull different people is self regulation for whatever reason.
Fixed: Earth is known by most humans as the only planet to have life.
every horrible thing in history, every holocaust and slave trade, every excruciating death,
is probably playing out countless times over throughout the universe.