You need to call $8 to win $21.
Sets can be cracked on say paired boards, Say your holding 88, and the flop comes Q, 8, J, but your opponent has something stupid like Q8- and the turn cones Q, and he shoves, you call, and the only thing to save you now is an 8. Lots of pain on a paired board. Just be aware of your opponents starting hand range, bluff tendencies, etc. Good luck... remember sets are crackable, but tbey can be powerful.
Do you have proof?believe me in pokerstars sets are so common you will lose a lot... I can't believe in one table one player got 6 sets and i lose 3 times to that player. The other players also lost a lot of money. Pokerstars is doing that all the time