They may outgun a single person but they won't outgun a large scale uprising. You're also assuming the police and military will always obey orders, which hasn't always been the case, especially when government goes dictatorial.

We haven't (thank god) had a situation in the USA where actually shooting at law enforcement is a good idea. That is, where you're literally at war with the government and trying to replace it with another one, which will in turn recognise your actions as not against the law. On the other hand, things like home invasions happen daily.