In particular, he says an inexpensive DAC from any Chinese company will do better than the expensive stuff. He says fancy audio gear is a waste of money because the data is already bit-perfect. All DAC chips sound the same. Am I being mislead?
I’m not sure about whether you are being strictly mislead, but perhaps your cousin brother is generailzing in a manner that is disingenuous. There are only specific instances of what he says that are representative of the current state of things.
This is confirmed by his own proclamation that he is an expert audiophile who claims that ASR has all the answers. There is a flaw - an internal inconsistency - in that statement.
Do your own research and avoid folk who generalize, however well-meaning.