Ah, but humanity is an expansive and consuming force, as is natural since most forces in the universe are entropy increasing ones. And since amino acids have been discovered on asteroids and tardigrades and fungus have been shown to survive space travel, we can't even say that Space provably lacks biological matter. Expanding (back?) into space is our manifest destiny, and good for the price of real estate too since all of earth becomes a luxury destination.
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Population growth has been slowing for a long time, and is actually already below replacement level in most parts of the world outside Africa. It's unlikely that we will ever reach a global human population of even 11 billion. Some estimates put the peak at under 9 billion.