Since most people are spoon-fed from the media, I doubt you know that this ‘single demographic’ represents about 50% of the voting public.
I am a retired professor (political science) and a conservative. I am well aware of voter demographics. Granted, this electoral season is different but I still think that what I have noted is generally correct and not a matter of conjecture or media influence. Trump has the opportunity to moderate and spread his appeal but has shown little inclination or capacity to do so.
Having said that, I was shocked in 2012 by an Obama second term and would have never thought millions of conservatives did not vote because they did not like the GOP nominee.
Trump has BEEN CLEAR that he will moderate for the November election. Right now his job is to keep his plurality of supporters fired up to vote for him, so he knows they need red meat. If Hillary somehow makes it to November, Trump will have a LOT MORE ROOM to maneuver.
By the way, what, exactly, is the starting point for people like Jeb? Basically, he’s looking for big-government Republicans (i.e., Common Core) that like Open Borders. I would estimate that base to be 10% of the electorate, at best. Trump is in a MUCH BETTER POSITION going into November than any GOPe could ever hope to be.