People still run the large bitcoin collider hoping to find key collisions haha.
Discussion
As an experiment a few years back I set up a server that was just generating private keys 24/7 and checking to see if it already had a balance. I ran it for a month on a pretty fast server and it didn't find anybody's Bitcoin. Even if you put all the computers in the world toward that task you probably wouldn't find any keys that were already in use.
That sounds like a fun experiment for an idle server. I know the LBC "puzzle keys" got solved but people at least knew what address spaces to look in for those so it doesn't really count.