Though Wikipedia itself says that:

The word is thought to have been first used in 1954, but was popularised in 1997 with a PBS documentary of the same name and the subsequent book Affluenza: The All-Consuming Epidemic (2001, revised in 2005, 2014).These works define affluenza as "a painful, contagious, socially transmitted condition of overload, debt, anxiety, and waste resulting from the dogged pursuit of more". A more informal definition of the term would describe it as "a quasi-illness caused by guilt for one's own socio-economic superiority".

The term "affluenza" has also been used to refer to an inability to understand the consequences of one's actions because of financial privilege.

So the first "popularization" seems to frame it more as a negative thing even for the self, while other definitions fit the case of Ethan Couch/Musk. Seems like the two definitions are pretty much opposites that use the same word, it's kinda confusing honestly lol