[ShamelessC]

> Have we considered AI and ML as a general brain replacement is a failed idea?

Yes. It is currently known to fail at this prospect. It is an open research question as to whether current methods can be merely "scaled up" using more compute to achieve "general brain replacement". I personally am skeptical about that considering basic problems such as concept drift (but I am by no means an expert).

You define what constitutes as valuable to be arbitrarily difficult/inconceivable with current methods (because it's an area of open research) and then say we should divert course merely because we don't know it's possible?

> never call AI a waste, it's not. But getting it to do human things just may be.

It already can do things thought to be previously exclusively "human" (such as beating Go). Recently it also helped make significant advancements for protein folding which are sure to yield benefits to medical science at least indirectly. I believe this statement is either incorrect, or you're expecting people to have some strange definition of "exclusively human", which is of course also open research and unanswered.