Because cheap fossil fuels's benefits will dissipate in two decades if we can move to green energy while the downsides project into whatever time remains of organized human civilization.
The point isn't that they're wonderful, it's that they're treated as this thing that only a few have benefited from, when it's exactly the opposite.
It's literally just a couple of decades of effort what separates the scenarios between mild climate change and the accelerated extinction of most of humanity and biomes. All so that Saudi Aramco and Chevron could get a bit more profit.