The continued existence of humanity and life in general is a good in itself. Besides that, why would you think that space exploration and colonization would reduce living standards?
Big goals take sacrifice and hard work. Any cosmic human diaspora would require sacrificing earthly abundance and leisure, and the colonists wouldn't be having a good time either, so the main beneficiaries would be the billionaires and politicians that could wave their dicks around about how they're responsible for sending man to the stars.
Chelyabinsk should have been that wake up call but most people don’t think about it deeply enough to realize how much worse it can be.
If we’re unlucky then the first big impact we experience will be our last.