Comment by Cthulhu_

Because that would mean they were wrong and their faith was misplaced. Faith is a good word to use in this case, because people like this are AI evangelists, going beyond selling it as "it is good because objective reasons 1, 2 and 3", into "this will revolutionize the world and how you think". They will overhype it and make excuses or talk around its flaws. Some of them are true believers, but I'm convinced most are just trying to sell a product or themselves.