Only some are more culpable than others. The climate crisis represents the single biggest failure of humanity. How stupid do our leaders need to be to know about an extinction level event (or at least one that threatens the breakdown of civilisation) with > 50 years notice and take no substantive action? They should be charged for crimes against humanity.
The blame doesn’t lie just with leaders though. It comes all the way from the bottom. Everyone wants their standard of life to improve, they want conveniences, luxuries, socioeconomic status… and they vote for policies that’ll give them those things. It’s a collective problem at a global scale.
Some people just want power and ego and status, some people just want things to be simple and not change from what they know, and a significantly smaller number of people just want to be chill and sensible.
Some conspiracy theorists warned people about the design of your political systems but no one seemed to think it's a legitimate concern. Time will tell I suppose.