I think the problem is the idea of the wall is now in popular culture to stay. I never thought he'd be able to build it, it's a ridiculous notion. A lot of people, apparently, thought it was a great idea, and even though it will never happen, they will now use the idea of it as a vocal weapon.
“Eternity is a terrible thought. I mean, where's it going to end?”
― Tom Stoppard, Rosencrantz and Guildenstern Are Dead
― Tom Stoppard, Rosencrantz and Guildenstern Are Dead