If law abiding gun owners were stripped of their means to defend themselves, their homes, and their families, then the two million or so DGU's each year would result in a successful crime.

That's certainly not true.

To start off, some chunk of those "DGU's" are going to be situations like the one Dope mentioned earlier in the thread. Guy's in the backyard, tries the door handle, and when an occupant shows up to the door he just leaves. If that occupant had a gun, they would have reported a DGU. But the gun had nothing to do with the crime being stopped - it was just their showing up that stopped it.

But there's another, more problematic chunk as well - the less tragic version of the situations we've mentioned on this thread. Guy goes to the wrong porch, pulls into the wrong driveway, tries to open the wrong car, kids play in the wrong yard - but instead of the occupant shooting and killing them, they shoot and miss, or just threaten them with a gun. The occupant thinks, "I've just prevented a crime!" - but the reality is that they just terrorized an innocent person.

The way these DGU surveys are conducted is all-but-guaranteed to generate these false positives. The surveys that yield these high numbers don't investigate or try to confirm the circumstances in which these "DGU's" happened - they just ask people if they've used their guns to defend themselves within the last X years. Of course people look back and decide that what happened was a DGU. "What kind of person threatens an innocent with a gun? A bad person. I'm not a bad person. So the person I threatened with my gun must have been about to commit a crime against me." That's why the results from surveys like the two million figure (which is probably the Kleck and Gertz survey from the mid-1990's) are wildly inconsistent with actual crime rates, often by an order of magnitude.

No, guns aren't preventing two million crimes per year.