Question

What causes the shepherd boy to become distracted and, as a result, lose sight of the young man who is holding his money?

Answer 1

What causes the shepherd boy to become distracted and, as a result, lose sight of the young man who is holding his money, is that he sees a beautiful sword in a vendor's stall. 
He was chasing after the man who stole his money, but became immediately distracted upon seeing the sword that he would like to have. He became mesmerized by the sword, thus the man with his money escaped from him and he couldn't see him anymore.