Democratic rule does not prevent tyranny it is not exempt from injustice and immorally. Review the history of Athens if you want to understand this better.
Even far from it!
There is no way to prevent tyranny in a group of different individuals in my experience. Whatever the group and its members, whatever the system, there will always a time where a large majority will say "we do this" ignoring de facto a minority who will get imposed something they don't want.
Democracy is a beautiful word but hiding a complex submissive/dominant reality. People are uprising when you say that democracy isn't perfect and isn't moraly good, that it's just an organization system that has its flaws...
I would say that democracy is a bit better over complete dictatorship but there must be even better forms of organization keeping more freedom directly in the hands of the people.