Decoys can make a burglar paranoid
We’ve already explained the importance of decoys, but their significance is much deeper. This person used the old glue-a-spare-key-under-the-floormat trick and noticed several burglary attempts over the years. He had cameras installed, too, for good measure. The OP noticed a similar pattern amongst the would-be burglars.
They’d try to pick up the key, only to realize that it was glued down. This would immediately put the would-be burglar on high alert. Thinking they were a part of a prank or even a trap, the bad guy would promptly leave the scene. Their paranoia skyrockets when they think they’ve been one-upped.