People don't understand how the caucus system works. They don't understand the difference between the Primary process and general elections in November.
Trump exploits the ignorance (not stupidity - okay) of his supporters.
The sad thing is that the supporters of Cruz and Trump and everyone else aren't supposed to know the vagaries of the delegate selection process in every state and territory.
But, the candidates and their campaign "professionals" should. If Trump's supporters are angry about Colorado, they should be angry at Trump and Corey and Manafort and the rest for being lazy and disengaged in a State nominating process where engagement and involvement mean everything.
Cruz is showing himself to be a pro. Trump? Not so much.