Props are now the third highest paid position in the NRL, so it doesn't seem like the NRL clubs agree with the idea that Haas is the only one worth 1million.
Players worth are market driven, and good props are the hardest to find on the market. Thats why when good ones become available, teams are willing to overpay.
There are more fullbacks that make up the top 20 players than in any other position, but theres so many more good fullbacks. Teams are more likely to let good fullbacks because they're so easily replaceable (eg. Parra letting Gutho go to get Iongi on 300k). There are so many teams with 2-3 NRL level fullbacks. Hopoate, Fa'alogo, Fletcher Sharpe, RTS, Jye Gray, Chevy Stewart, Campbell, Brimson etc etc are all playing out of position or in reserve grade because of the quality. Good fullbacks are easy to come by, but good props are the hardest to come by. How many gun props of that type of quality are currently in reserve grade?