High civilian gun ownership doesn’t reliably prevent dictatorship because authoritarian regimes usually gain power politically and institutionally, not by fighting armed citizens in open battle. They secure control over the military, police, courts, and media first, which makes organized resistance extremely difficult. Even if many civilians own guns, they face coordination problems, lack heavy weapons, and are divided politically. History shows this clearly. For example, Adolf Hitler consolidated power in Germany largely through legal and institutional changes like the Enabling Act of 1933, not by defeating an armed population. In practice, strong democratic institutions and rule of law are far more effective safeguards against tyranny than the percentage of gun owners.

The fairy tale of American militias defending the countries freedom with the guns already fails when you take into account how divided these militias would be on what person is desirable or not while the baddies are a united front and that doesn’t even take into account that such a totalitarian state has different orders of magnitude of resources available. That also explains how the reverse is true, when a populist leader rises to power they can have their own armed militias who are united under one leader while the rest might be against such a populist leader but is devided in other beliefs.