That's right! The question is which direction that tyranny would come from? The founders weren't worried that they themselves would direct that tyranny, so they placed the "Army Clause" in Article 1, Section 8. The states demanded the Bill of Rights as a precondition to ratification. They were worried that the officer corps of a large standing army posed that threat - something that a civilian militia wouldn't.When the Amendment was written, the People were the militia. And the militia (the People) were the defense of a free state. It was specifically written to prevent tyranny by a large central government.
The body of the Constitution states that the government only posses the power granted by the enumerated rights in the document. The 2nd Amendment makes the formation of a militia by the government constitutional - you can even see this in this our governments response to external threats prior to WWII. We maintained a small, relatively weak federal army that was bolstered by large volunteer militia formations.
The paranoia of the government to a great extent was a product of the 1960s. So too is the idea that Americans must be armed to the teeth to hold a hostile federal government at bay. At least own your paranoia @Injun - the Founders weren't worried that they would hold a gun to their own heads.