I was just thinking recently about what would be needed to make the government fall. Have political enmity, racial and cultural divisions, economic strife, lawlessness, then call election outcomes into question... occured to me that the last domino needed would be splintering of the military which would follow on quite naturally from existing political, racial, cultural, and economic problems.
Also occurs to me that anyone on either 'side' who thinks a civil war is fine is making the classic mistake of focusing all their attention on the other side. There's a lot more pieces on the board. A civil war would result in a global shift in the balance of power from which the US would be unable to recover. The military would become divided and ineffective. Bases would disappear, allies would be forced to make other arrangements, and our ability to project military dominance would be gone. Someone, likely China, would fill that vacuum, and fill it effectively enough that we wouldn't be competitive at all.
The threat isn't purely domestic. The world is a dangerous place. We can't have uncertainty about the transfer of governmental power. Extremely bad things could result. We need an agreed upon way to cast and count votes and a promise from both sides to honor the result. Whether you're liberal or conservative, 4 years of a president you don't like is preferable to the irrevocable fall of the country and Chinese global hegemony.