I totally agree that people who aren't committed to the Republican principles of smaller government, lower taxes, less regulation, balanced budgets, and more economic opportunity shouldn't be voting in our primaries .... or running as candidates.

That said, Trump surged out to a large early lead in winner-take-all or winner-take-most early "open" primaries where blue collar Democrats were allowed to cross over and vote for Trump.  Trump got about 35% of the vote and 60-70% of the delegates while 65% of the vote was split among 16 other candidates.  Open primaries were a huge mistake.