Cribbing generally starts as a response to pain, often from ulcers. If you treat the underlying problem quickly enough, the cribbing is less likely to become a habit, but it is an addictive behavior. Cribbing collars prevent the horse from actually cribbing, but don't treat the underlying cause.
I bought my cribber 4 months ago, but he's cribbed for over 5 years. He started before he was ever stalled, so contrary to popular belief, it isn't just a boredom issue seen in stalled horses. He has some other signs that he has ulcers, and I'm working to try and see what works best for him, but even when that gets resolved, I don't expect he will ever stop cribbing completely. The best I'm hoping for is that he will do it less frequently.