Mr. AndyinIowa, you have some great points that merit consideration by all reading.
For my part, I'll offer the following: My wife and children were in a car accident last October. A guy in a jacked up truck, stopped at a stop sign, pulled out and literally drove into the side of my wife's car as she drove past at 55 MPH. Fortunate he didn't pull out any sooner or she would have speared him and lost the "physics" battle...she was in a Land Rover Freelander and he was in a Dodge 3500. His bumper was so high, it mostly hit the passenger upper front quarter and doorframe...hate to think if I was driving and my wife was in the passenger's seat. After being "punted", she was rear-ended by another car before coming to rest in the median, children laughing because of the wild "ride". Got to love children.
My point: I spent $50,000 on the safest car I could find to put my family into...a Volvo XC90. $50,000 I spent on the off chance that lighting would strike twice.
Therefore the $500 I have invested in my gun comes pretty close to meeting your "100 times more likely" scenario since I have 100 times the money invested in automobile safety as I have invested in personal weaponry.
For the record, I have 9 smoke detectors in my home, don't smoke, and have a home security system with cellular backup (in case the phone line is cut) that we use religiously. It is almost never off, even if we are in the house.
We even have those silly ladders you toss out the 3rd story window in case you have a fire and can't escape. How many folks here run "fire drills" in their house? It's a pretty good idea...
So certain costs...and certain controvertial types of protection...CAN fit in the scope of normal home protection and be perfectly reasonable in cost, suitability, and overall risk.
As much as I hate to say it, we live in a world where folks choose to perform violent crimes. It really stinks and I wish it wasn't so. But I don't want to be THE ONE GUY bringing a baseball bat to a the fight. And in that moment, it doesn't matter if I die or if the other guy does...God's Will and all...but I want to at least be prepared. It's a little like having the power go out and not having any flashlights or candles. THAT'S pretty silly...it is so easy and cheap to prepare for these situations, but you don't think about it until the situation is upon you and you SOOOOO wish you had a flashlight.
And since moving to our smaller (100,000 people) town 3 years ago, there have been two families (as in: a household) killed. In one case, they took some chocolate chip cookies and $50...the other, a laptop and jewelry. NOT ME, BROTHER. There's going to be a fight in my house.