Cyber

This prefix comes from the field of cybernetics, which is the study of the command and control of groups and beings (yes, it’s very vague). It’s usage in that field dates to the 1940s.

That name came from the Greek “kubernetes” for “steersman” or “governor.”

Sometime in the 1980s, this morphed into a general way of referring to the burgeoning field of computers, and then in the 1990s it became a way to refer to the Internet.

Its usage as such seems to be related to how vague it is. It sounds modern, and it can apply to anything. It was just a neologism that got picked up into common usage.