To be fair, those are not things that are taught in school. If they come up at all it is in some historical context, a battle someone else fought--and won. There is no mention that maintaining a liberal democracy requires effort and vigilance. Modern, ie. post-WW2, "fighting democracies" have built-in safeguards to oppose internal enemies of democracy, but if they are effective remains to be seen. The USA mostly does not even have such mechanisms and it shows.