It's nice to see Lemmy will be continuing Reddit's tradition of believing booby traps are ok because anyone trying to touching your precious things deserves the be physically hurt, regardless of the countless ways it can hurt other people who were doing nothing wrong.
This example isn't even defendable from a home defense angle because you left the thing out on the damn boat, not locked away. At that point it's not just a booby trap, it's a baited trap.
And for fucks sake it's a damn cooler, who cares this much about it but leave it where anyone can get it?
You could also just put a fucking padlock on it like a sane human being.
At this point, you're not concerned with keeping your precious cooler, you're just looking to hurt people.