I read that to imply it was after he sold the $300M, not before - the article claims he already cashed that $300M out. Thus, the extra net worth he would have

I read that to imply it was after he sold the $300M, not before - the article claims he already cashed that $300M out. Thus, the extra net worth he would have gotten beyond the $4B would have been meaningless, whereas the $300M got him to the point where the IPO is meaningless. Based upon this, cashing out $300M would be extremely logical. But maybe my reading is incorrect.