I'd say it's largely due to the coming of age during the Internet era where there is much more visibility into the thoughts and inner workings of our political leaders and public institutions.
Plus some notable milestones:
2001 Patriot Act - very unpatriotic and anti-american
2008 mortgage crisis - huge bailouts for large corps, nothing for regular joes
2016 election of Trump - reality TV president, collapse of "norms"
2020+ covid response - unprepared and poorly handled, contradictions and backpedaling abound
Probably lots more I'm omitting but it's much harder to make the case we're #1 these days without adding caveats and qualifiers.
