Greta Thornburg and the state of science

I see the whole thing about Greta Thornburg, and  I just don't get it. I just don't see why this whole thing should matter to so many people. so, a new person showed up and so, she says what everyone likes? so what? there were once people who worried about overpopulation> where are those now? gone. overpopulation was a flash in the pan. there were once people who wanted eugenics. where are they now? they are gone. that is how it is with science. all a flash in the pan.