Let me sum the whole argument up. The 2nd amendment is often misinterpreted to mean that a militia is required for gun ownership. In fact, it is the opposite. Guns are required in order to have a militia. Put into simplified modern language, the amendment reads "Because we need a well regulated militia, we must ensure that the people have a right to carry weapons".
In other words, the militia is not a condition for gun ownership. Gun ownership is a condition for having a militia.