Crypto-currencies make a few people win out at the cost of others, who in hindsight mistakenly "invested". The ones who won evangelize it the most, but they don't stop and think about, where that money came from. Might be an uncomfortable thought. Then you have the hopeful ones, who hope to win out in the future. Basically all driven by volatility and the believe, that they will be able to exit at the right moment. And maybe they will be, but then others are the losers.

I don't find this to be an ethically OK way to act.