What does juan tomas mean when he says, "You have defied not the pearl buyers, but the whole structure, the whole way of life, and i am afraid for you."

The community worked with specific dealers, who had offered Kino a lot of money....... even if it wasn't what the pearl may have been worth. Kino defied the buyers and intended to leave the community and see if he could get a greater amount of money. His actions would not be respected in the community he lived in, and because of his actions the trade would change for everyone.