Yes, democracy is subject to a 51% attack, like blockchain stuff. Better than a 1% or 10% attack though. Some countries like the US have a constitution that can only be changed by a majority >> 50%, offering additional but still not full protection. This is why I mentioned it’s also desirable to have a common value system among the citizenry. In the end, a country has to be more than just laws and voting, and at some point people have to actually get along and make it work together.