If he wants to run under Party rules, he should let it all play out, because there are rules in place that aren’t going to change this election cycle. Maybe never.
But it appears that he counted on large crowds translating into a win, and it didn’t work out for him any more than Cruz counting on the evangelical vote in the south worked out for him. Facts are facts.
At this point, he has a plurality, as you know. He may indeed win the nomination, but he has not done so until he’s secured the 1237 delegates.
It is unfair and an exaggeration to claim Trump has expected to win only by “large crowds.” The truth is that the Republican establishment had pulled out all the stops to destroy its front runner - something that has NEVER happened before. The debacle in Colorado is just the tip of the iceberg. The GOP canceled their presidential preference vote, and then someone from the party tweeted that they were sabotaging Trump, then they deleted the tweet. We can go round and round the flagpole about “The Process” and whether the party has the “legal” right to destroy the front runner. Is it moral? No. It isn't moral. It is tyrannical, just as the Democrat “Super Delegates” is corrupt and immoral. Trump expects to win on votes. What a concept, huh?