It’s a great way to turn off regular people from whatever movement they’re pitching.
They may label themselves as environmentalists etc - because they have to label themselves as something if they don't want to just be considered vandals - but I think the answer that's most likely is some type of personality disorder.
1. Get in the news
2. ???
3. Environment is saved!
Allegedly, they did this to reduce the burning of fossil fuels, not (as seems more likely to me and others) to act like a bunch of poorly-socialized three-year-olds throwing a tantrum.
How many fewer barrels of oil would you estimate will be burned over the course of the coming year as a direct result of this "protest"? Say, to the nearest million. Be sure to show your work.
Any? No? Then it didn't actually "work", did it?