I don't think the level of investment in an idea is equivalent to how impressive it may be. Most of the investment in AI is based on the idea that it will make professions and human labour obsolete, which means whoever has the reins at the moment it "solves" the "problem" of human labour will effectively reign over everyone else. The level of investment is then somewhat orthogonal to how technically impressive it is.
Not to mention that the less easily-explainable a technical achievement is, the less investment it will attract simply because fewer people will grasp the ramifications. You can describe AI in two words ("machine human") while it would take a few more to describe compilers in an instantly understandable way.
I mean - I'd say electricity, agriculture, steam power, metallurgy, silicon computing (cmos), atomic power, the scientific method - these are _all_ very impressive - all lead to drastic changes for humanity. Not sure how I'd rank them.
I personally think AI will end up sitting in the top 3 of these - but that is an opinion. I do think it is obvious it is at least _somewhere_ in that list.
Not to mention that the less easily-explainable a technical achievement is, the less investment it will attract simply because fewer people will grasp the ramifications. You can describe AI in two words ("machine human") while it would take a few more to describe compilers in an instantly understandable way.