Trump was simply too late on starting the wall. They didn't do anything on it until last year. I don't think they've built very much. A cheaper plan would have been to end welfare. That would have kept out the Mexicans that just want to eat for free.
He stalled the project because his main backers, people like Paul Singer or Sheldon Adelson are for open borders and The Great Replacement of European Americans. The Wall was mostly a PR move to hold on to his electoral base.
The problem with Trump is that he is straddling two mutually exclusive constituencies, his populist voting base that want an America First agenda, and the globalist zio-cons that want open borders, lower wages, unlimited immigration and endless wars for Israel.
If Trump does make it next week, we'll find out where his real allegiances really lie...