This is a misdiagnosis. Lamenting that it's too late is the complete opposite of partying like it's 1999. We're not having fun. It's the climate change denialists who are partying like it's 1999, pretending that nothing has changed, that there's not a problem, and that we don't need to do anything. They're the ones who are complacent.
By the way, the lyrics of the song 1999 were very much tongue-in-cheek. Prince had a political streak, he had not given up on caring, and he wrote a number of other political songs, such as "Ronnie Talk to Russia", "Annie Christian", "Free", "America", and "Pop Life".