I'm also in the camp that definition of luxury is a moot point.
Take a look at this Bloomberg survey of 5000 Tesla buyers.
https://www.bloomberg.com/graphics/2...evolution.html
1. It seems that all carmakers get hit - Honda, Toyota, Audi, BMW, Mercedes, etc.
2. People do complain about the build quality of their Tesla Model 3 but overall they are happy and tend to recommend it to others.
3. The lower end BMW (3/4 series), Audi (A4), Mercedes (C Class) are particularly vulnerable to buyers jumping to a Tesla.
So regardless of what the definition of "luxury" is the impact on the vehicle market as a whole has been significant.