Why are we so mean to each other?(Let's get together)?

If we could just come together and put aside our political, racial, etc differences and give each other big hugs, we would all be happier for it? Let's just be friends. No more republican v democrat, conservative vs liberal, anarchist vs libertarian, black vs white, illegal vs legal, keynes vs mises, marx vs smith, obama vs paul, maher vs o'reilly, trump vs obama, kim vs paris, hitler vs jew, kkk vs nation of islam, etc,etc.......Let's just be friends..