It isn’t OUR job to fix the underlying problems in other countries. Keeping those problems from spreading into OUR country is our job, and physical barriers are a key tool to doing that.
A good %-age of the criminalian problem is folks just overstaying their visas. A wall is a must, but not the only solution to the problem of foreign invasion that we should deal with.
A wall to deal with invasion by foot.
Putting teeth into Visa overstaying to deal with the soft invasion by Visa.