Sounds about right. That's pretty much the way it's been all along, through the campaigns too.  Trump always had a strong core support in the 25% neighborhood, but then it dropped off sharply with most everyone else.  Including many Republicans (thus the unprecedented opposition from within his own party, although I still find it a little hard to consider Trump a Republican in the first place).  Trump was either your first choice, or your last choice. He was almost no one's 2nd choice, or 3rd choice, or 4th choice.  It was all of nothing.

Fortunately for him, in the primaries he got to run against an overcrowded field of 17, where 25% support can win.  And in the general election he got to run against someone even worse (Hillary).