Most people get their opinions from the people around them, and the media they consume. If the media talked about them in a better light, it would change people's opinions on them. People also hate the idea of being mildly inconvenienced, especially since most of the progress we've had from technology has been about improving convenience.
I don't boo them. But their message is equivalent to "let's lose over 90% of Earth's population over a couple of years" which isn't too popular for some strange reason.
A better message would be "let's use all what's left of fossil energy to build out renewable energy infrastructure and downscale our lifestyles radically, as the time is short". While still losing a lot of people, but that part is not said aloud.
