Earlier quoted context omitted.
I don't like the framing of the behavior as somehow irrational or random or clinically-diagnosible. It's not irrational to get involved more in a movement when it is a movement, and seems like it might be gaining traction. Just like it's not irrational to not-boycott some useful, cheap product even if you strongly disagree with some of the practices that go into its production, but to join a boycott if it starts and…
Objectively speaking becoming involved in a trend only for the sake of a given trend becoming more trendy strikes me as directly irrational. It’s following for the sake of following only because that’s what followers do which is circular and absent of any original consideration.
Of course, if you're saying society at large is irrational I pretty much agree... but within the context of social expectation, I'd say it's pretty rational to compute that your contribution is more likely to land once a movement has already started. If anything, those who first begin the movement are the most irrational (since the likelihood of success is much lower compared to the personal cost to the individual).
In other words: if you live in an irrational system, the only way to be rational is to behave irrationally.
EDIT: Italicizing.