you do have a point. however thats the most accurate and only trackable information on the net you can find. it doesnt even include cash games... so while e.g. Phil Ivey could be winning 1 mio in tournament winnings in 2016, he may have lost e.g. 0.5 mio in cash games. BTW the buy ins (especially for WSOP events) are mostly given to the pros by their sponsor (FullTiltPoker, 888 Poker etc.)