When Trump lowers the facade and shows us who he is, his ratings go down. Then he puts on that fake ass act and his ratings go up again.
Trump supporters don't like who Trump really is and if he wins he won't put on an act for 4 years
Also, polls today do matter! They matter for fundraising, swaying public opinion and the elections going on this week (Paul Ryan, etc) there are local elections for house / Senate going on from now until Nov. 8.
Anyone who says today's polls don't matter are truly clueless
