The problem Adam Ruins Everything he usually only cites sources that tell part of the story, which when looking at the issue as a whole, makes his arguments very misleading.

He is correct many of the illegals do fly over and overstay their visa, but that is only part of the problem with illegal immigration. In fact in his video, I think he even states it is only half of illegal immigration anyways. What about the other 50%? The 50% that won't be issued a tourist visa are criminals, or individuals who aren't eligible for one reason or another, and they need to stay out. The wall doesn't stop 100%, but it will stop 50%. The 50% we already don't want here.

That is the 50% we need to worry about stopping. Obviously we should also make some reforms to stop illegal immigration through visa overstays, but we are already a step ahead there in that we actually know they are in our country, have their names, etc. They are less of a threat since we are able to at least vet them initially.

The wall stops those we need to focus on most. Then lets worry about the others.