Bill Clinton tried to explain away why people who work in the coal industry won't support Hillary when they voted for him in the '90s, and chalked it up to some sort of irrational paranoia. Direct quote: "They blame the president when the sun doesn’t come up in the morning now.”
That makes no sense on any level. First of all, when does the sun not come up in the morning? If it didn't, we'd all be dead, and nobody would be around to blame the President for anything. Besides, the only people who think the President controls the sun are liberal environmentalists. Putting that aside, I have more faith in the intelligence of people in the coal industry, who understand that the closing of hundreds of mines and the loss of over 80,000 coal jobs is largely due to the current President declaring open war on their industry, announcing to the world that he was going to drive it into extinction, and then turning the EPA regulators loose to do just that.
And this is just a shot in the dark (the sun having not come up today and all), but maybe they don't support Hillary because she's promised to continue those Obama policies and said that under her energy policies, “We’re going to put a lot of coal miners and coal companies out of business.”
Coal industry workers don't back Hillary for the same reason that the Clintons wouldn't support anyone who vowed to pass tougher transparency and ethics laws for non-profit organizations. It would put them out of business.