What does the mob do when someone actually can't pay up?

Rewatching Artie's Armagnac Saga and thinking to myself, what if Jean Phillipe is just a complete deadbeat who can't pay up?

Like what if the Armagnac was genuinely a complete scam to rip off Artie. What if Jean Phillipe is a broke bastard with no assets. What do the mob do to collect? Like they can threaten violence, break his legs, but ultimately bad debts must eventually arise in this thing of ours? Killing the guy solidifies nothing's ever going to be made whole.

And then when you consider the type of desperate fucks turn to the mob for cash, it's gotta happen that sometimes they just can't pay it back no?