It's a sad truth that a thief will be able to get through any bike lock, given enough time, the right tools and the know-how. What's most important is that you insure your bike, so that if it is stolen, you are at least covered. Your insurance will specify the level of security you need, with more expensive bikes generally needing Sold Secure Diamond or Gold ratings.
Locking your bike securely, securing both wheels and the frame to an immovable object will help to lower the chance of your bike being stolen, as thieves tend to go for easier targets