This is not accidental. There is more genetic variation in humans in Africa than the whole rest of the world, and more variation in English dialects in England than the whole rest of the world. We -- everything we knew existed until recently -- evolved from extremophiles. They came first. The world changed around them. Some changed to match, eventually giving rise to us, while others found places more like what they were used to. The latter are still to be found in those places, and in many others they have also adapted to.
Common types like us are adapted to currently common conditions. When the environment changes radically, and all the life we knew of up until recently is extinct, the extremophiles will radiate a new ecosystem adapted to new conditions.
We have exactly one example of an environment that nurtures life. It does not logically follow hence that it is the only environment where life can thrive (unless we choose to define life as that which thrives in an Earth-like environment)
I do agree that probably most of the Universe is hostile, not only to Earth-like life, but to life of any definition. But we cannot be certain. We have never visited nor sent a probe to a 5g planet "100-1000x the solar irradiance, the lack of magnetic field (and thus direct exposure to solar winds), no atmosphere, or atmosphere entirely composed of a toxic gas, extreme exposure to X-rays".
I'm more of the "Boltzmann Brain" persuasion. Life might take the form of electromagnetic waves or metallic structures that are respirating, self-replicating, information-processing things. In my more paranoid days, I think the internet is alive, as it is kind of like a life-form growing our the substrate of our collective digital actions.
Not really. They are all within +/-5km of the planet surface, live under 1g of gravity, as a rule, are not exposed to X-rays, gamma rays, cosmic rays, strong magnetic fields or nuclear radiation, or extreme temperatures. There's nowhere on Earth that receives more than about average solar radiation or gets much above 100C where life survives.
Life generally has access to ample oxygen, though a few anaerobic organisms exist. They're all DNA-based, have access to ample amino acids, aren't bathed in thousands of completely toxic chemicals, have liquid water (and not, e.g. liquid methane). The list goes on and on.
Yeah, there are a few extremophiles, but they are by far the minority, and are clearly adapted incrementally from other organisms that evolved in non-extremophile environments. In essence, there's a large reservoir of easy-pickins living that generates biodiversity to cross over into extremophile environments.
Now imagine 5x the gravity, 100-1000x the solar irradiance, the lack of magnetic field (and thus direct exposure to solar winds), no atmosphere, or atmosphere entirely composed of a toxic gas, extreme exposure to X-rays, etc. The universe is full of many places where Earth life, even extremophiles, would have no chance of survival. And such places don't have reservoirs of biodiversity from which to adapt to these conditions. They're just dead.