The Idea behind this is the concept of smart money and Dumb money on the market.

The "taxi driver" is the Dumb money, the mass of people that heard that buys stocks/cryptos is easy money and everyone Will be rich.

What happens is that this huge amount of money drives the price up quickly, but these people have no Idea what they are buying, and what make the market movements. And they dont Care about this information, only that someone told him that he is going to get rich quickly. And they buy the asset at a high price.

The smart money know How this Works, and when It sees this, there is a huge profit taking, wich causes a bid drop in price. The Dumb money panics, start to sell more and the market drops even more.

This Will also happen with cryptos eventually.

That doesnt mean that cryptos Will disappear, but It Will be the time to learn wich are the solid project, that Will actually have value in the Future.

Thing is, the crash Will come some day, but when and How big is something kind of Impossible to know for sure, since this is a totally New tech.