I've noticed that sometimes more expensive bikes simply don't get stolen while cheap ones do. I assume that's because of an easier market to sell them. There was a period when my son's children's bikes got stolen all the time, while my far more expensive cargo bike wasn't, despite it being only locked with a ring lock, and no chain. But of course a kid's bike is also much easier to pick up, and it had a very light lock.
In London, most stolen bikes are expensive (or expensive-looking) and they are primarily resold within London.
So true. Many people seem to imagine bike locks as an arms race between owners and thieves, but it's an arms race between owners and other owners. The role of thieves in that arms race is more like that of a judge than like that of a participant. Well, unless they refuse acting in that role and just pick up the entire rack...
https://www.youtube.com/watch?v=ODIkw4MAeVg
(language warning if you've never seen the show)
All that is needed is to be the least stealable bicycle in the rack. In my case this means two locks of different kinds. It's a big deterrent and they will move on to other, easier targets.
If you can avoid being the lowest hanging fruit, you will probably be alright.