I think Cryptocurrency is not a bubble, the term "bubble" is used by crypto to liken the increase in bitcoin prices that are so high that the term is present.
source https://www.google.com/url?rct=j&sa=t&url=https://bitcointalk.org/index.php%3Ftopic%3D3275880.1940&ct=ga&cd=CAIyGmM2Nzk3ODA2ZWViNjVjODI6Y29tOmVuOlVT&usg=AFQjCNEVkJ2j8h-8I_aYUU9_kmFyFw1IhA
