Tony Chen even addresses this directly in the video above.
They literally had a hard line in the sand. $600. If it costs more than $600 to hack it then they really don't care.
The other big thing is games being locked to a specific OS version, meaning some games require updates to play them. This has been key in their security strategy. It's basically pointless to hack it, it will be patched and you'll have to opt in to the patch to play anything new.
Another smart move by Microsoft was shipping Xboxes in an uninitialized state that has to connect to the internet and download the latest firmware before it can be used. Sony has been repeatedly burned by patching an exploit but having the vulnerable firmware still pre-installed on machines still in retail channels, so someone willing to abuse return policies can easily get one. MS doesn't need to worry about that, every new Xbox ends up on the latest firmware regardless of when it was manufactured.
They literally had a hard line in the sand. $600. If it costs more than $600 to hack it then they really don't care.
The other big thing is games being locked to a specific OS version, meaning some games require updates to play them. This has been key in their security strategy. It's basically pointless to hack it, it will be patched and you'll have to opt in to the patch to play anything new.