Unfortunately there are only 10,000 ways to combine a 4-digit number. But there are combinations that can be easy to remember for the user but harder to guess.
Is it really stealing when you have no money in your account?;)
I love the comments at the bottom of the thread that point out that, because they listed - I think it was 8086 - as the least-often used combination, it would immediately become more popular, and thieves will now try that one!
Actually, maybe I should change my real one, but it's not one of those no-brainer combinations, and I've never had a problem. I'm a firm believer in the old saying - "if it ain't broke then don't fix it" :p