This is a clear case of gambling addiction. He couldn't control his gambling activities which was why he decided to gamble on credit. In some physical bet shops, you have to pay before you place a bet. It is usually written boldly in these bet shops that you have to pay or deposit money before placing a bet. A long time ago when my friends used to engage in traditional games like cards and dice, you could use your belongings to gamble. There are times when some of them will have to go home on just inner wear because they have gambled with almost everything they own including clothes. An addict always has hope that the next bet will favor him and that the next bet could turn into more bets.
Some gambling addicts also have some traits of greed or lack of contentment. This is why you will see a bettor, gamble out of all he has won. They are not just satisfied with what they have won, thus they keep placing bets until they lose all they have won.