The eventual goal of researchers is to create General AI. The opposite of Weak AI, General AI can outperform humans at nearly every cognitive task. As discussed on Comment Central, the existence of an entity that can completely replace humans will, psychologically speaking, really mess humanity up. When AI can out-think us in every respect, what are humans for? It’s human nature for people to struggle when faced to survive a meaningless existence.
On top of existential problems, people will also be isolated more and more. As a general observation, the increase in technological advances enables humans to live independently of each other. Where other mammal creatures cozy up for comfort, humans have a tendency to want personal space (when was the last time you enjoyed sitting middle seat on an airplane?) Technology isolates us. And to comfort us, more technology is developed as band-aid for the loneliness void. It’s a solution-less cycle.
And of course, there’s the old-fashioned fear of AI becoming too smart for its own good and overthrowing humanity completely:
"Intelligence enables control: humans control tigers not because we are stronger, but because we are smarter. This means that if we cede our position as smartest on our planet, it’s possible that we might also cede control."