For long, ordinary citizens have been considered bulwarks against democratic decay. Yet, recently, assaults on democracy were undertaken by rulers who came into power through citizens’ sovereign choices. Why do citizens so frequently fail to stand up for democracy although the democratic idea is almost universally supported? To resolve this paradox, in this review article I introduce “democratic support as truism” as a novel conceptual lens. Citizen support for democracy is a truism in that it is a widely held but superficial attitude. In other words, almost everyone supports democracy but only few can explain why they do, or what democracy is. From this perspective, the foremost danger to democracy is not that large swaths of citizens would oppose democracy and might become active agents of democratic overthrow. Instead, due to a shallow understanding of democracy’s underlying principles and practices many citizens fail to recognize democratic norm violations and become easy targets for the manipulation by aspiring autocrats who frame their assaults on democracy as pro-democratic. As a consequence, even though democracy remains as popular as ever, against more sophisticated forms of democratic backsliding the citizenry is a more fragile line of defense than previously considered.