Doubt there’s a BMW enthusiast that will go out of their way to repair a 2010s diesel.

You're blowing it out of proportion. A repair like that costs between 1-2k euros. Even non-enthusiasts are repairing that, at least those outside of wealthy western Europe.

No, you need to change the whole engine if you get chain timing issues. And a new engine is more than the car itself.

Not when the car itself costs about as much.

For a manual 335d people would yeah.