It's not actually insane at all if you think about it.

There could be a reason for someone to need to break into your apartment, like the emergency services, or someone escaping a natural catastrophe or a murderer. Anything could happen. And at that point, when running away from a hurricane/murderer, you shouldn't have to assume any and all private property may be boobytrapped.

It's similar to but not quite the same as why rape shouldn't have the death penalty. Sure, intuitively one might think that's justice. But if you take the thought longer, you'll realise that giving the death penalty for rape just means that any rapists could murder their victim as well, without it actually changing the punishment. Which means it would always be the logical choice for rapists. Meaning victims of rape would also be victims of murder.

Now obviously no-one wants to be raped, but if you had to choose between being raped and being raped and murdered, I'm sure most at least would choose the former.

If boobytrapping homes would be legal, then the emergency services could reasonably just refuse to go anywhere where there can be traps. And thus you'd end up burning quite a lot of people and people trying of relatively easy to fix medical issues.

I too, would enjoy seeing a thief get something blown off, but do we want boobytraps so bad that we don't care about how many people die from the lack of emergency services?