“Virtue-signaling” is just another though-terminating cliché of the current culture wars. It implies that the action has no cost to the person and provides some social credit. These people are risking their lives, violence, prison time, etc. Everyone hates them. Nobody knows their names. They keep doing it. Your hypothesis doesn’t hold. If we all decided that we don’t give a shit about this civilization-ending event, might as well through some soup at a van Gogh painting. Why not? It won’t matter anyway.

Even if these people were horrible “virtue-signaling” vandals, it is a microscopic problem in comparison to the real one: clime change. And yet the media focus on the former. Why? You do the math.