Reasons not to kill everything...
There have been mass extinctions before. They're not even that rare: moments in the fossil record where everything disappears, one Friday afternoon, and mostly never comes back. And yet here we are. Living. So life may not be that easy to kill. It may not even lie within our power, not a thing we can actually do: to crash the world so hard not even bacteria in the bedrock survive. Which is not to say we can't lose everything we care about: elephants and parrots and squid; not to say it cannot only be in one billion years, when the bedrock bacteria finally invent palaeontology, that they look at our particular stratum and say "Bloody hell! That was a harsh one..."
