Trump supporters turned out to be 47% of voters and it's been said many times he had a strong base of energized young people. It's entirely possible it's fully legitimate in my mind at least.
From what I've read, Trump didn't actually get any more votes than republicans in the past few presidential races, it's just the democratic turnout was a lot lower than expected, i.e. fewer people overall voted (or more voted for the third-parties).