I think you're underestimating how many people support Trump merely for his "deport the 11 million" platform.
And in some respects, Trump's platform on illegal immigrants is correct. The left is throwing a fit because Trump wants to deport millions of their voting bloc. Hispanics will never, EVER, en masse, vote for anything resembling a conservative platform. Look at who runs their native countries and who they vote for once they arrive on our soil. A libertarian paradise will NEVER exist if the nation becomes majority Hispanic. With a Hispanic majority, you will only get Progressives.
Rand's biggest mistake was making the NSA--an issue most Americans still don't understand--one of his main issues. Trump talks in a way that most Americans can relate too, whilst Rand talks in-depth about the NSA, when most of the GOP base probably doesn't even understand how to shit-post on Facebook. However, most Americans DO understand that they want every single illegal immigrant gone.
Trump is genius for making this his single issue. I guarantee that he's taken notes on Nigel Farage.