Furthermore, if there was no reason to have lost the eyes, those cave fish probably would have kept them. It wasn’t use it or lose it, it was just wasted resources on a vulnerability. Since the eyes weren’t necessary to see and they were vulnerable to damage and infection, it was actually safer to not have them. There is no perfect evolution or end goal. You are right to think that evolution can lead to dumber people because intelligence isn’t necessarily the goal of evolution or even the “more evolved” state because there is no real goal for evolution. If we get to a point where our intelligence is a detriment, we might lose it, but I doubt that would be the case considering it can just be utilized in other ways. Also, even with automated systems and AI, you’d think someone would still need to use their brain to utilize or fix these systems.