How does Steinbeck reinforce the evil actions of the pearl buyer

Steinbeck shows the evil of the pearl buyers through the way they work together in order to cheat Kino. The first buyer claim it has no value, that it's worthless like "fool's gold". Each of the subsequent buyers acts much the same, and the pearl's value is set, lowered, and highered a bit in order to get Kino to sell for a pittance of its worth. The buyers work together against Kino, and in effect, the pearl becomes exactly what they say..... worthless. The buyers wish to devalue the pearl and cheat Kino, leaving him frustrated and without alternatives.