ixnay00 is right and in the last 100 years its been a lot more than 56,000,000 people murdered.
If you look at history you see that many governments took advantage of their people when they had the power to do so. That is the main reason for the 2nd amendment. We shouldn't be so naive as to think it can't happen here. Power tends to corrupt and I don't want the government getting any more powerful in relation to its citizens than it already is.