The 2nd amendment doesn't protect against tyranny, the democratic rule of law does. The US just (barely) voted in an autocrat ffs and for most of its history only rich white men had full rights and freedoms. An armed populace didn't even stop hundreds of years of slavery in the US or in many other armed countries. Germany was well armed when Hitler was voted in and the Nazis even loosened gun restrictions.
Further, take a look at the countries with the most armed populaces. Many are the most oppressive and illiberal in the world. en.wikipedia.org/wiki/Estimated_number_of_guns_per_capita_by_country And the US is far from the freest country by any world freedom or rights indices, just like many heavily armed countries.