Wouldn't the loansharks threaten to kill Larry's dad?
With someone like Larry, they would realize that beating him up would have no effect on him. He still wouldn't pay.
Wouldn't you think they would threaten his father to get him to pay? They knew where Larry lived. Suppose they showed up one day and his dad said "Larry's gone. He left." You think the loansharks would just say "Oh ok he left? have a nice day, sir."