There is a strange and powerful drive to be the first person to declare that something has jumped the shark. I don't know exactly what it is about the Internet that has done this, but the time it takes for someone to leap up and declare that something is "over" just keeps going down, to the point that it has now reached somewhat absurd levels. Maybe we're in a bubble, maybe not, but either way the declaration seems to be getting made on awfully scanty evidence... but it's important to be first.

Of course on a long enough time scale a bubble in tech is inevitable almost no matter how you slice it.