Hash competition from life might cause them to go extinct, and even if it happens again it just gets out-competed to extinction fast.

I always found it odd that there's only one single origin of life point or even just a single common ancestor considered in history. Shouldn't entirely new life develop all the time on earth? I mean the ingredients and building blocks are still there, the environmental situation still should work out, like availability of water, temperatures, etc. We should see a constant emergence of new life all the time. Why would that process stop, just because some other life already exists? Maybe we just can't detect this, because whatever new life happens to appear —more or less— resembles life that's already there.