It has been scientifically proven that viewing patriotic displays like the flag, hearing the anthem, and even watching fireworks, makes people feel and act more conservatively. And the effect can last for a month or so. All the patriotism and greatness plays into Trump's overall message.
Meanwhile Obama and Hillary would tell these athletes, "you didn't win that!". No, the government paved the road you used to get to practice every day, so it was really the government that set you up to win. Your individual effort meant little.
That is why the Dem convention was completely devoid of flags until it was called out and then for the last night, they handed flags out to the audience.
It's also why liberals complain about the anthem before sporting events and they are trying to stop the Yankees and other teams from playing God Bless America during the 7th inning stretch.
That and liberals hate freedom and America.