2. Overhype. The "Internet of money" and "adoption will be just like the Internet" and "it's inevitable!"
DVD was "the future" and "the best image quality possible"... Until it wasn't.
You know what was poised to take over transportation? Segway.
The past is littered with short runs, unfulfilled fantasies, and cults of people sure about a specific thing happening in the future.
There are infinitely more things that *can* happen than you can imagine. As you get older, you see how few things happen as you expected, and usually, that's fine. The world doesn't end. And, usually, better technologies win out. Bitcoin is a great (and fun!) hobby for the young, but for the wise, diversification and hedges are necessary to minimize risk and maintain peace of mind.