there are billions of planets with the same conditions as ours in our galaxy alone, before you even get to the 2 trillion galaxies in our universe and then potentially trillions of other universes
and if life was common we would have been visited by or seen evidence of alien life by now
there is without doubt a great filter that prevents life from spreading throughout the galaxy, if we have not already passed the great filter (highly unlikely, we've not been capable of anything to wipe out an entire planet before) then it is something that all life stumbles upon, for that to be the case it has to be something that seems completely safe and is easy enough for an advanced civilisation to do
fusion will be the end of humanity, there is no way a civilisation with near unlimited power created by fusion would limit itself to one planet and stay vulnerable. Hence the great filter has to be something civilisations achieve BEFORE space colonisation, but at or beyond our current level of technology
we are very close to the end of humanity