Keeping out the barbarians!
This is not a wall intended to keep the citizens inside the country, like the wall in Berlin, but the kind to keep out bad people!
Civilization always had to protect itself against barbarians. Under the Biden administration, they allowed 12 to 20 million illegals to flood the US, with terrible consequences, as they imported violent crime & imposed horrendous costs on the communities that actually tried to house and feed those illegals - with a massive increase in the cost of real estate, as it is simply not possible to create enough housing for them. Many clearly came with the goal of living parasitically on US wealth without contributing anything.
The wall worked - they only managed to cross the border in large numbers where there was no wall or where government agents opened doors and removed barriers to let them in, on orders from the Biden administration. They then distributed them across the country & illegally provided millions of them with social security numbers.
Many libertarians don't understand that legal & immigrants are radically different types of individuals. Legal immigrants commit crimes at very low rates and are eager to work hard to earn personal wealth, while illegals commit crimes at very high rates - especially violent and gang-related crimes. Illegals are also involved in human and especially child trafficking.
The more free a society is, the greater its wealth generation, the greater its need to protect itself against hostile forces that want to rob them of the wealth generated by the people in such a free society. Mass migrations from 3rd world countries into western countries are financed and organized by the UN & various foundations that promote the UN Agenda 2030 / the Great Reset, which want to establish a world government.
Now the most important task is to fight the barbarians already inside the gates, cf. Thomas Sowell's book ("Barbarians inside the gates")!