IMHO the law of diminishing returns applies to those who have limited financial resources to spend on audio gear, while still trying to get the best sound that they can for their audio dollar.
For those who have what is essentially endless financial resources, they can afford whatever audio gear they desire, while enjoying this hobby at a level that most of us can only dream about.
As always, this is just my subjective opinion and should thus be taken with a grain of sand. 😊