It seems to have taken on a literal narcissism in the Snap era.

Narcissism and materialism can be very different things

I agree. You could even call this flavor a sort of immaterialism, a preoccupation with what isn't actually real.

>Western culture is probably the least materialistic of all major cultures

Is this sarcasm? What are you basing this on? I don't think I've ever heard anyone opine this before.

Probably the Chinese concept of "face".

https://en.wikipedia.org/wiki/Face_(sociological_concept)

I wouldn’t call it the least materialistic but capitalist culture is dominant in most of the world now. Honestly I think the lack of materialism in most cultures is largely mythologized. If African tribes measure your wealth by how many animals you have, well, that’s just materialism via other materials and I’m sure leads to its own kinds of conspicuous consumption (invite the whole village to your party for instance).

Religious orders seem to be the easy-to-identify exception and those exist in all the large cultures.