President Trump signed an executive order on Wednesday to build a massive southern border wall, fulfilling a key campaign promise he made to his supporters during his presidential campaign.

Or so he would like them to think.

No matter the “alternative facts”, Trump can’t sign a wall into existence with an executive order. He still needs Congress to approve the $20bn price tag in federal funds. Environmental hurdles like deserts and mountains must also be overcome. Ranchers and private landowners probably won’t roll over and just give the government their land without putting up a fight in court.

Even if these problems magically went away, experts say that such an undertaking could take up to 16 years. We as a country swang from Barack Obama to Tweety McTangerine in half that time. Assuming we survive that long, it seems unlikely that Trump’s vanity project will have the time it needs to be built. He didn’t even take office with a popular mandate, after all.

As for Mexico paying for it, well, as we say in Spanish: “No.”

Of course, that doesn’t mean nothing will happen. He will probably beef up border security. Deportations will probably increase. If he does manage to get funding for the wall, it will be at the expense of us taxpayers. Most tragically, families will be ripped apart.

But don’t let Trump get away with pulling off this publicity stunt on his own terms. Let’s instead see this executive order for what it is: yet another unhinged act of aggression in his ongoing war against reality.

The executive action is a symbolic gesture before it is anything else. His followers will eat it up, and the experts and the facts will contradict him every step of the way, but it won’t matter. All Trump cares about is the part where he personally benefits. It’s how he does everything. It’s how he got to where he is today.

Just look at the other things he’s “built”. Trump University, beset by lawsuits for allegedly defrauding students – he has always denied the claims – and operating without a license. His casinos in Atlantic City went bankrupt, while he boasted that he “made a lot of money” from the project. He makes big promises. He stiffs people. He comes out on top. That’s his game.

This big, “beautiful” wall that was the keystone of Trump’s campaign is just another Trump scam. In many ways, it’s the perfect encapsulation of who and what Trump is: smoke and mirrors. A fake.

Trump would prefer to live in a fact-free world where reality isn’t there to remind him that he’s not who he says he is. He dismisses these inconvenient reminders as “fake news”. Usually in a tweet. Usually in all caps.

But facts do matter. They matter whether Trump likes them or not, and they are true whether Trump likes them or not. They are worth saying often, and they are worth saying loudly at a time where the government is making a concerted effort to sweep them under the rug.

So here are some facts. We already have 700 miles of border wall. More people are returning to Mexico than are crossing the border into the United States. It has been shown that immigrants actually help our economy, not hurt it, and benefit native-born workers. Undocumented immigrants do pay taxes and social security and are far less likely to commit crimes than native-born citizens. Finally, increased border security has not curbed the influx of undocumented people.

These points are unlikely to sway any of Trump’s ardent supporters. But it’s not about swaying them. It’s about telling the truth. It’s about not letting an authoritarian tell us what is real and what is fake.

This executive action, this impossible wall, is not a fulfilled campaign promise. It is a tribute to Trump’s narcissism. It is an example of how willing he is to scapegoat a group of people for personal gain. It is a fitting monument for an unfit leader.