It’s a well known phenomenon that the more people self-compliment about some great quality they have, the less that is the case.

A similar thing seems to happen at a political level - the countries were politicians just harp on and on about how great their Democracy is (in the case of the US) or how old it is (in the case of the UK) have the most flawed Democracies (if they even count as Democracies given how far they stray from the “all votes are equal” criteria) whilst in the best Democracies out there (like The Netherlands where they have Proportional Vote) they never talk about how great a Democracy they are.

I believe it’s called Overcompensation.