Youth definitely plays a big part in this feeling but I think the dotcom era was also somewhat historically unusual because two huge external events happened around the same time: anyone old enough to grow up during the Cold War had lived with this constant feeling that their life could suddenly be destroyed (as a kid in the 80s we still had air raid drills), and then suddenly people were having rock concerts on both sides of the Berlin Wall while the victorious United States and European allies stopped worrying about the Fulda Gap and started welcoming new NATO members.

The second big change around that time was the internet tearing down cultural borders. Anyone could participate, even people who’d been trapped behind the iron curtain just a decade before, and many people were predicting that the free flow of communication would strengthen democracy and ensure the fall of Chinese authoritarianism.

(Far fewer people correctly predicted that the second would imperil the first)

It was also an era before the paranoid security of the appartus of the state slammed down hard post-9/11.

By which I mean we could do "illegal" raves in abandoned warehouses or spontaneous outdoor spaces and not end up (generally) in holding cells.

After 9/11 the consequences of perceived deviancy became far more extreme.

That and the absolute wave of decentered distraction of social media hadn't arrived yet. There was still some sense of shared common cultures, rather than a bazillion fractured windowless monads fed through social media and Spotify feeds