Trump is correct on his history. Reagan skipped the 1980 Iowa debate, as he considered himself the inevitable nominee. He then had his clock cleaned in Iowa by GHW Bush. To his credit, Reagan rushed to New Hampshire and arranged for his own debate. He went on to win NH and then the nomination. Trump should take note.
Reagan didn’t lose Iowa because he didn’t debate. He lost because the Iowa Party apparatus was controlled by Bushies. The caucuses were run pretty loosely back in the day and allowed for plenty of party shenanigans. They may still be ala the Iowa democrat debacle last time around.
My first caucus in ‘76 was Ford vs. Reagan and after being told to “go make your voice heard at the caucus” they weren’t even going to take a vote in my precinct. I asked what was going on and a show of hands was made for the candidates. I doubt the information wasn’t even conveyed to the State party. I felt cheated and mislead and the GOP got a fifty year pain in the butt. The party is just reaping what they’ve sowed for decades with Trump: embrace him. He’s good for what ailes us.