What proportion of the NFT mania is actually artists making money vs grifters and scammers making money?

If there are artists making money that previously weren't then that proportion is irrelevant. It's a completely voluntary system, no one is forced to use it or care about it.

Except for the many artists who are having their work stolen.

Those are unauthorized. Too bad to the collectors who gave their money to scammers, but those NFTs are worthless the moment the artist declares them forgeries.

Worthless according to who? It's not like the artist can take ownership of the NFT

The value of an NFT is in its provenance, just as with traditional works. If you forge a Mondrian, it won't be worth as much as an original Mondrian. It's even worse for NFTs since anyone can own the file data; the value of the NFT is almost purely its relationship to the artist.

Artist making a fair living sell their art, this selling of NFTs is not them selling their art, they are selling an immaterial bragging right. It's insane.

It's irrelevant what it is or isn't, people are paying money for their art. How can you tell someone like this guy https://twitter.com/deekaymotion who recently starting making good money off his work that he's a grifter?