Last night's televised Oval Orifice address (which, I'll admit, I haven't watched) and the general response to it make me think of Dr. George Lakoff and Caitlin Johnstone. Both these writers have important, Big-Picture things to say about this and related issues—and how the Democrats lost 2016. (Hint: It wasn't Susan Sarandon's fault.)
Liberals and progressives have been trying to argue against the border wall using facts, statistics, and reasoning. That's a great approach if you're trying to convince other liberals and progressives. If you're trying to convince conservatives, or win elections against them, or talk to people who don't claim any ideology (Obama/Trump voters), facts and reasoning are mostly ineffective. Too many conservatives and non-ideologues care less about documentable facts than about whether you're telling a good story.
Yes, policy should be evidence-based. Not so long ago, in my lifetime, even Republicans believed that. But if you trot out facts and stats in your electoral campaign, you risk losing your audience.