First their generation creates a problem thinking it won't affect them and now that it starts threatening themselves they suddenly start having a problem with it - exactly my mind of humour...
To be less cynical, it's possible those venn diagrams don't overlap, or they've changed over time after removing layers of ignorance. There doesn't always need to be massive hypocrisy behind every motive, nor do we need to immediately shove our fingers that direction. Sometimes the world comes around to where people who thought this all along are now given a pulpet with which they will be finally heard.
Why do you blame an entire generation of people?
You think the average Joe is directly responsible for climate change?
You can blame leaders, politicians, etc who actually had the power to change things and the responsability to be aware of climate change and take action.
And if you say "yeah but they elected the politicians" I don't know what it's like in Sweden but in a lot of countries you have no meaningful choice. You have Trump vs Biden kind of options, always having to vote for the "lesser evil".