Think drugs, terrorists, cartels, etc.
I will 'think' about those things once was have some hard numbers from reputable sources.
For example, how many terrorist acts were committed based on people coming in from Mexico? And as for drugs, if you want to eliminate those, just legalese in the USA. Presto, no more market for drug dealers.
Just seems silly to me to contemplate spending 40 Billion on something - Money that could go to education, healthcare, veterans - When there doesn't seem to be hard facts indicating that that spend is a good investment of tax dollars that will solve a real problem.
I'm a fiscal conservative, so I need to see the numbers first, before I can get behind something like that.