Why is so much time and effort spent into AdS/CFT when we know for sure that we don't live in AdS? I'm no cosmologist but the word around the block is that our universe is decently approximated by dS space. I know that a dS/CFT correspondence exists, but I rarely ever hear about it, if at all.

Sure it's fun to think about hypotheticals, and perhaps one could (in principle) specifically engineer systems to exhibit an effective AdS metric, sorta like how you can trick anyons into "existing", but if the goal is to understand quantum gravity at a fundamental/cosmological level, shouldn't we be focusing on our actual reality?