I think the issue is that the border is already pretty damn secure and net immigration with Mexico has been near 0 for nearly the past 10 years.
It's a lot of money being thrown at a problem that isn't as big as it once was.
Hiring surges in the border patrol has actually been shown to make us less secure in the past and the sections of the border that aren't walled, aren't walled because of lack of funding or initiative, but because they're some of the most deadly deserts on Earth.
The problem we have isn't the flow of illegals into the country anymore, it's integrating or removing the ones already here.
I think the money would be better spent modernizing the Border Patrol and Coast Guard, and the Coast Guard in particular as way more trafficking and smuggling goes on in the ocean these days, and creating a path to legal citizenship or at least temporary status for those here or working toward removing them.