Everything Bubble
en.wikipedia.org
en.wikipedia.org
Is Amazon a bubble? Is Netflix a bubble? Is bitcoin a bubble? Is Uber a bubble? Is the dollar a bubble? Are near zero yield bonds a bubble? Even if you agree on the general premise of the everything bubble, most people would disagree on the specifics and it is at least within possibility that this bubble melts up and never pops.
So basically, call it a bubble when it bursts, and put your chips on the table until then.
That's how bubbles form. The rationally irrational know there are gains to be had by being irrational. It's pretty sad that this is something to brag about.