He founded a single start-up when he was 19 that failed in its mission and was bought for a paltry sum (for YC, anyway). Other than that his experience in life and business consists primarily of having been born into affluence and all the privilege and advantage that brings.
It's so very Bay Area for someone like him to be president of a VC firm. His pre-YC resume wouldn't get most people past the resume filter in almost any other company, including a number that YC fund.
And most of his comments about business are not all that useful. They're exactly the sort of comments I'd expect from someone blessed with great luck and above average intellect but too little experience.
He was also a successful angel investor and I think a scout for sequoia before YC. I think he was more successful at the angel investing thing than at his startup