People love to repeat this myth, as if most human beings won't care about others or about their own future, as if they can't understand enlightened self-interest, or can't understand climate change. Mostly, it's yet another argument for powerlessness and inaction.
The public has gotten behind so many things now and historically. Right now they are the power behind movements that have nothing to offer but brazen falsehoods, corruption, and hate. And yet all the good people say, mass movements are impossible, there's nothing we can do but suffer.