Yet for all that in 7 years as shift sergeant on an autocrime team I (and the team) never came across a Disklok that had been successfully defeated. Quite a few where Billy Light fingers had a go with all sorts of hardware, but none that came anywhere near close to being overcome.
Indeed, we would often come across CCTV where the scumbags would roll up, eyeball the Disklok, have a quick conflab with lots of head shaking, and then clear off and steal a similar but unprotected vehicle from up the road because they knew what the odds of winning were.
The Diamond has a particular blend of steel that is particularly resistant to attack, especially by grinding or drilling. Because it's stronger it doesn't need to be so thick in the less critical areas yet still provides the same level of resistance to attack. If you and a chum could snap the pin by hand that can't be cut by an angle grinder I'll donate £50 to the charity of your choice.