Everyone who is surprised how popular Donald Trump has become among many of the GOP haven’t been awake for the past 8 years. He is the male equivalent of Sarah Palin.
Both know nothing about the world and cover up their lack of knowledge with provocative language. For them, that's easy to do. And their followers in the GOP lap it up. These GOP 'macho' followers did it in 2008 and now they are doing the same thing in 2015/16. The 33% percent of the GOP who loved Sarah, and love Donald, are easy to find - just ask who hates Muslims and Mexicans (oh, and Jews, Blacks, Asians, etc.) If they say “hell yes I hate them”, then they love Sarah and Donald. Donald and Sarah speak at a 2nd grade level which is about their followers' level of thinking.
So stop being surprised Trump is leading in the polls. He will continue to do so, and the only lucky thing for the rest of us (and the world) is he won’t win the Presidency… just like Sarah could never win.