Yes and Great Wall didn't stop the Mongols from invading China (bribery did them in)!
Personally, I'm not opposed to the wall, but I'm not convinced that in it's current form, that it's the best bang for the buck (see Maginot Line during WW2, Atlantic Wall, etc). Do we know for a fact that this is what our border guys want?
Walls don't work in stoping military adanvces anymore. Which is why the Atlantic Wall failed. However they work great at stoping immigrants.
Granted, the wall in its current form is useless against a concentrated tank attack, but so far the illegals have not used that technique.
"Do we know for a fact that this is what our border guys want?'
At this stage, we know that the illegals DON'T want a wall, and that's a good enough reason to build one.