I find myself falling into this line of thought a lot: why should we make tradeoffs that favor the earth instead of hyper-accelerating progress to get off of it in preparation for its inevitable demise?
But isn’t the entire universe also going to meet its end as well, in an anticlimactic heat death? To overcome that, a civilization would have to reach universe-level Kardashev-like energy utilization capability, which would necessarily consume every particle in the universe, including themselves. It seems infeasible and unwise.
Maybe it would lead to the next big bang… but that still is a death and rebirth.
I think ultimately folks that support post-earth transhumanism operate on a notion that they themselves or their direct descendants that they will know and love in their own lifetimes will benefit from this space-colonial survivalist utopia. But IMO the reality is that if it is even possible, it would only happen long, long after they and everyone they could know or imagine are dead. It would likelier be accomplished by a society and civilization that they would hate and believe should be exterminated, due to the tradeoffs that would have to be made to accomplish it.
It’s essentially an individual’s desire to live forever and avoid death, projected onto the human race. I’m not convinced it would actually be nice to live forever. Better to focus on how to make the short time we have be as good as possible. IMO the idea of eternal life leads to all sorts of perversions of the now in exchange for an assumed eternal afterward.