Nah, this ain't it IMO.

"Cool" is nebulous and ephemeral, and defined by being unforced and difficult to pull off. The majority of cool things and people tend to burn bright and quick. It's also very relative in a social sense. (What's considered cool in rural Nebraska is definitely not cool in LA, at least not at the same time.)

Being the right person (or social group) in the right place at the right time, being of another time (including future) or just having a particularly unique sensibility can all be factors.

Once something cool becomes widely popular, it tends toward commodification and watering down, and that is the opposite of cool.