Oh that would be so much fun for me. But I am always prepared for that and would be the worse nightmare for the thief or bad person. The main reason for doing this if for the protection of my other family members. Plus make the front of the house look nicer with more curb appeal.
If there was no restriction, I’d renovation and put in a basement. That’s adding 30% to my living space, and the kids would love it as a games room. Unfortunately, underground strauctures are not permitted here as we are a below sea level delta *smile*.
I have a full basement with a walk out. It is very nice almost doubles my living space. If I place in a couple egress basement windows I will have almost the same livable sq ft in basement as on main floor.