The problem with predicting bubbles is that there is a huge amount of psychology involved and if something is fickle and hard to predict, it's surely humans. Something has value only while enough market participants agree that it has value and as human behavior is often illogical and emotional, the market is capable of doing some strange things sometimes.

But the point made by the article makes a lot of sense even on the face of it without even considering the math. Most of the people participating in the cryptocurrency markets right now are still mostly people that firmly believe in the concept. Their overall confidence makes the system stable and value continues to climb. A lot of those people are in it for the long run and are very unlikely to sell in panic, so as long as they are the majority, you could say that there isn't a real bubble or that a bubble would be hard to pop. This type of problem can arise only when enough people that are more skeptical of the concept enter the market, so their irrational behavior can start swaying it.