Nobody knows “humanity’s long term interest” with any certainty. Consider that fossil fuels allowed humanity to make massive technological advancements in a relatively short time. Yes, it caused climate change, but perhaps those same technological advancements allow us to fix or adapt to that. Then, in 500 years, another disaster like an asteroid or a solar flare or the Earth’s magnetic poles reversing or whatever happens, and without the boost from fossil fuels we would have been too technologically behind to be able to survive it. What was in humanity’s long term interest then?
I’m not saying that’s definitely the case, but moving slowly when you live in a universe that might hurl a giant rock at you any minute doesn’t seem like a great idea.