Since the notion of More CCW = Less crimes assumes the bad guys have a running knowledge of CCW data, then they would have a running knowledge that of the CCW folks in a given state likely don't average more than 4% of adults.
You're assuming that criminals would have to have knowledge of CCW data. They wouldn't have to. If more and more people are carrying, it stands to reason that more and more criminals are running into good people with guns. I don't know the minds of criminals, but it stands to reason that having the business end of a gun pointed at their face could potentially make them rethink their life.
I'm making an assumption here too. The problem is there are several factors that could be involved. This could be one factor.
I don't mean to nitpick, but your post is full of assumptions, and light on facts. You assume that only 20% of CCW holders carry. You assume you can tell who has a gun in the house, and who doesn't. The risk of a criminal running into a CCW holder is enough to keep *some* (probably a small percentage) from committing a violent crime. Even if it's only a few percent who stop, or slow down their actions, it would still be a statistically significant number.
But again, I'm assuming also. Correlation is not causation, and we need to be careful to make the claim that higher CCW relates to lower crime. All we would need is for some anti-gun think tank to "prove" some other factor is at work, and then we have egg on our faces. I tend to believe that higher gun ownership, and more people carrying guns have an effect on crime, but I would never say for sure that's the reason.
This is important. Most pro-gun people would say the two aren't related. But they seem to be correlated. I think there's probably another factor involved. But if we keep spouting off "more CCW = less crime" expect to get stuff like this thrown back. Also, I just washed my car, so obviously, it's going to rain.