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.
What, the government's own study says that illegal immigration has decreased dramatically, and that illegal immigrants commit far less crime than native-born citizens? "Doesn't matter. The gubmint lies. Fox News just told me that 3 million illegal immigrants voted for Hillary. Who ya gonna believe?"
Lakoff has been saying it for decades in books like Moral Politics and Don't Think of an Elephant. The "Strict-Father" Conservatives have been attracting votes from the same people they're out to screw by constructing a winning narrative, mostly with metaphors about the nation as a family and the president as the National Dad.
Johnstone will tell you that, in the Information Age, those who control the narrative control the world, and those who control the media (big corporations) control the narrative. As a result, the Information Age is characterized by increased DISinformation and MISinformation.
The "left" (broadly defined) needs a good story of its own. How did Bill Clinton win in 1992? Apart from the 1991 and Poppy Bush's sinking approval ratings, Team Clinton concocted an excellent story, mostly about how Bill was a working-class kid from a small town with Big Dreams. Also, "It's the economy, stupid!" because in 1992 it absolutely was. Forget foreign policy, human rights, etc.: The voters had no problem with Bush's military interventions in Panama and Iraq/Kuwait, which were actually quite popular at the time.
Donald Trump won working-class votes in the Rust Belt (and elsewhere) because he told a story those voters wanted to hear. He told it more effectively than the other Republican candidates and, improbably, won the nomination. It didn't matter that he made stuff up, contradicted himself, and spoke like a random word generator. The corporate media fed it all to working people, and working people ate it up. Hillary Clinton ignored the Rust Belt, hung out with Wall Street and Hollywood mega-donors, and making everyone see the Democratic Party as the party of the élite.
You can't win with facts when your opposition doesn't give a fuck about facts. They might respond to "facts"—either taken out of context or outright lies—that fit the narrative to which they subscribe. Their narrative tells them that the border wall will do everything His Trumpness says it will.