At the end of the day it doesn't matter how well you protect the car.
Bollards, deadlocks, immobilisers, jackstands etc.
If someone wants it, they'll take it. I've seen cars stolen that have been up on hoists with no engines behind bollard shilded doors. Most classic/enthusiast car thefts aren't spur of the moment smash and grabs, people stake out the places for months before doing the deed.
I remember listening to a podcast ages ago where they interviewed an ex car thief who said "I don't care if you park it in your damn bedroom with you, if I want it, it will be mine."
I've got double barrel deadlocks on each end of my shed, CCTV, fuel pump killswitches, and other cars parked in front of the door. But I still wouldn't consider my car "safe" in the area I live.