Commentator and general firebrand Pat Buchanan asks that question in a recent op-ed, available here. As the former Reagan communications director and three-time candidate for the presidency writes:
Neither George W. Bush, the Republican Party nominee in 2000 and 2004, nor Jeb, the dethroned Prince of Wales, will be in Cleveland. Nor will John McCain or Mitt Romney, the last two nominees.
These former leaders would like it thought that high principle keeps them away from a GOP convention that would nominate Donald Trump. Petulance, however, must surely play a part. Bush Republicans feel unappreciated, and understandably so.
For Trump’s nomination represents not only a rejection of their legacy but a repudiation of much of post-Cold War party dogma.
America crossed a historic divide and entered a new era. Even should Trump lose, there is likely no going back.Buchanan is gloating a bit in this piece, which is understandable given his political career in the 1990's, presenting an anti-war, anti-illegal immigration & anti-free trade platform in his primary battles for the GOP presidential nomination in 1992 and 1996, and in his Reform Party run for the White House in 2000. In the 1992 GOP primary & the 2000 electoral campaigns, he ran first against George Bush the Elder and then George Bush the Younger, presenting precisely the economically nationalist agenda that has been echoed by Trump's campaign thus far.
In that sense, Trump's victory over the Republican Party's entrenched elite represents the fulfillment of perspectives first championed by Buchanan (and also Ross Perot in his independent runs for the presidency in 1992 and 1996) now almost a quarter of a century ago. Buchanan's whole piece is worth a read, to understand what is motivating much of the Establishment GOP's hostility to Trump's candidacy. Of course, as this piece over at the Law & Liberty blog points out, the national Elite has a good deal of hostility to the vast bulk of the citizens of our nation. This animosity is leading to significant problems for the Elite's effectiveness.
Update: of course, for those in the GOP less than enthralled with Trump's Buchananite leanings, there are other reasons they might want to cast their vote for Trump, principally, he isn't HRC.