That's the rub- how much is enough? When designing buildings to withstand natural catastrophes, you always consider how strong the earthquake could be, how high the flooding. More protection gets expensive, and resources are finite. Too much and you waste your limited resources, too little and you risk devastation. And of course you can't possibly protect against every threat. I'd love to have a fortress that would offer total protection but that structure doesn't exist. I have to ask what it will cost to defend against likely attacks. It's probably not within my budget to install doors that can withstand a fire axe, and in any event the walls would have to be similarly reinforced.

At the level I can afford I want to keep out the honest people, and the lazy. As I can afford it I'll try to keep nudging the bar up one notch at a time.