Is child labour caused by poverty? ??

No. Every child desperately wants to join the grownup world. The first time a boy makes a profit on something he wants to do it again right away. Every child is an eager capitalist. He feels cheated when he looks for a job and learns that it is a crime to hire him. That is a large part of the reason why so many teens feel sullen: they have been forcibly excluded from learning how to act like a normal person. They are forced to pretend to be children for years after childhood has ended, and then one day people start scolding them because they don't act grown up. And nobody can understand why it happens that way.