why? Because the history books and graveyards (marked and unmarked) are full of examples of hundreds of millions of unarmed powerless peoples being marched off to their deaths by power-hungry dictators and their supporters. The authors of the American political system were exceedingly well educated and understood that a new American constitutional republic experiment where the people held the power would revert to a dictatorship unless the people themselves had some mechanism to retain authority. In addition to the checks and balances in the government, a large part of that authority is established (and guaranteed) through the availability of militarily-useful firearms as a last resort.