Most humans live their lives completely disconnected from the rails of progress. Most don't need a grand ambition to be satisfied, instead they get by with rewarding distractions that keep their minds from collapsing inwards.

Remember the brain evolved to serve the body, not the other way around. Happy body, happy brain. I'm sure the AI will figure out how to pacify the population should that be its goal. Humans existed happily for at least 2 million years - most of which had almost no scientific progress, it's not required for a human mind. An ASI could easily revert human society to this sort of simplicity as the "ultimate" solution.