[chippy]

Many of those fads or movements are not sub cultures because they are part of the larger culture. But more so, many subcultures are dead because they became part of the larger culture. The other examples - "NRX Silicon Valley techno-libertarian sub-culture" probably is a subculture. It certainly sounds like they have founding principles and differentiates itself from wider society. The same would go for Red Pill etc examples, as they would be more along the line of anti mainstream political movements. I'm not sure they have coolness though!

From wikipedia: "a subculture is a group of people within a culture that differentiates itself from the larger culture to which it belongs, though often maintaining some of its founding principles."

Those who do selfies are not identifying themselves as part of their own group, and separate from the larger culture. Even the early adopters of the selfie never thought of themselves as a subculture, just cool within the larger one. STEM and celebrity worship also could be seen as part of the larger mainstream. Just because something is fashionable or cool does not make it a sub culture.