It's a connotation of Fad, Scam, and useless. But it's a electronic innovation We view this sometimes as useless but let's look at dot.com era like eBay and Amazon certainly many dot-com company failed but they were hit by lows but at the end they were able to escape the possible demise. The difference between electronic innovation and physical one is the adaptation. Cryptocurrency development is very quick that it makes them look like bubble.