You know you’ve made it in your genre when you have laws of magic named after you, and Brandon Sanderson does have two laws of magic, though in his case he came up with them and has written essays and made recordings about them, they have gone on to become popular and accepted laws for magic systems in the fantasy genre.
Sanderson has been writing epic fantasy since he was a teenager, and wrote a large number of books before he got his first one published. He has gone on to publish a number of standalone novels, as well as a trilogy and the first tome in an epic ten-book series. He has also written young adult series and novels, as well as short stories and novellas all set within the fantasy genre.
So he’s put down a lot of words in the world of fantasy, and has also talked a lot about the genre and writing, and has brought a wealth of experience and knowledge to it, easily making him one of the more respected and best fantasy writers writing today.