Yes. All security devices are breakable, it's just a question of deterrence. A thief is going to think twice about doing too much hammering in the wee hours, especially as many of the cheaper or more common nuts can be got off quietly with the right tool. Some of the better nuts can't be removed with pin wrenches, and would take a *lot* of hammering, these are usually enough to persuade a thief to go in search of easier pickings.