It's a common symptom of the Gartner hype cycle.

This doesn't mean that there aren't very valid use cases for these technologies that can benefit humanity in many ways (and I mean this for both digital currencies and machine learning), but unfortunately those get drowned out by the opportunity seekers and charlatans that give the others the same bad reputation.

As usual, it's best to be highly critical of opinions on both extreme sides of the spectrum until (and if) we start climbing the Slope of Enlightenment.