Stupidity, that's why.

Those uppity cosplayers are still around?

Like who and what policies were put in place in to promote race war?

"Chris Hill, a paralegal who goes by the code name "Bloodagent.""

Pretty much all that needs to be said.  There is nothing quite like a chuunibyou with a real weapon.

You forget Trump Jr.'s comparison of Syrian refugees to Skittles.

Mass immigration, economic policies that concentrate more money in fewer hands, promotion of white guilt, etc. Not sure I'd say they were put in place to promote a full on race war, but definitely some powerful people have found it very useful to inflame racial tensions as we can see by the increased fractiousness throughout the entire western world in recent years.

As for who... well, if you look at the forces arrayed against Trump you'll have a very good idea. Like him or not, he's not the cause and until their legitimate concerns are addressed the movement behind him isn't going away regardless of what happens Tuesday.

Pretty ironic, since Trump is more likely to start race wars himself.

Pretty ironic that he's not the one who divides people up by race and panders to them or pits them against each other as needed, then fucks them over as hard as he possibly can until the next election when he needs their vote again. You know, the kind of stuff that does actually lead to race war.

Would a few hundreds of people be enough to start a Civil War ?

Mass emigration? To where and by whom? That's a pretty broad statement.

Which economic policies were put in place to concentrate more money in fewer hands? We all know that conservatives love trickle down economics because rich are so good to us bottom feeders. Deregulation, corporate tax breaks, we all know whose spell book hammers down those words.

Promotion of white guilt, I'd love for you to explain that one. Like, people are promoting self flagelation of white people or what? 

Oh yeah some powerful people have inflamed racial tensions but look who's been promoting racial wars and prepping in the woods of Ohio, Kentucky, etc..., with paramilitary equipments. Who's been funding them?

Forces against Trump are reactionary ones to his asinine claims and statement. No one is gonna sit on the sidelines and let another person difame them and spew lies about them.

Even The Crusader has jumped in because they felt their time has arrived:

http://www.nydailynews.com/news/national/trump-endorsed-kkk-neo-nazis-america-white-article-1.2543847

Under president Obozo, 13.3 million jobs were created and out of 44 presidents he stood on the 4th place for most job created. But hey, its easier to run the unclear ruinous economic policies narrative.