Is a 2000 mile wall practical? I don't think so.
Are walls in general effective to stop people? Yes...and we should be able to agree on that.
So, building walls at commonly used crossing points, or to form choke points, would be an effective use of tax payer dollars.
I agree that building the wall as a monument for Trump is not a legitimate basis to support the wall. But, opposing a useful wall as a component of border security because the Left cannot allow a political victory to Trump is not a legitimate basis to oppose the wall.