Could be isis, Russia, China (Just the fact of possibly diverting resources or time), money marketers who bet against the dollar, the republican party. Sure there is more.

Sales of defensive guns would increase.

So, persons interested in the opportunity this presents may also want to look at investing in whiskey distillers and producers of chewing tobacco

Maybe this belongs in Creative Speculation but this election could just be 'The Art of the Deal'.

And bow much civil unrest are we talking about? Just frequent riots and dangerous streets in certain places? Or looting on every neighborhood across the country?

If we are talking full on civil war, with factions, it really depends who bands together. If we are talking just rioting and dereliction of everyday life, the military industrial complex benefits to some extent as marshall law would certainly be declared.

The middle class, as always, would suffer, and small businesses in particular, as there would be less commerce.

If we are talking something that could effectively end the stability of the government, global corporations probably benefit and we see shortly corporate militaries, with each corporation acting as its own government. Note that this may simply be accelerating an endgame that may be inevitable at this point anyway.

Which I should do anyway, living in California...

water, emergency food, extra gasoline, maybe a generator (small)...

but I've been thinking to add one more thing (which even drives me crazy to admit that I think about it)... a gun of some sort.