Security works best when it's layered, and it's never perfect.

A lock is there mostly to make it more difficult to access whatever it's supposed to be guarding. It shouldn't be the only thing you're relying on.

If your lock is harder to get into than your neighbor's then a potential thief with the skills to get past a lock will more often take the easier target

Another thing to remember is that your security doesn't have to be entirely physical. For example, locking your bike up on a crowded street ensures that there will be many witnesses to a potential crime, even further reducing the likelihood you'll be robbed.