It is always about the person at the time and isn't it possible that they might mature with age? Age shouldn't be dismissed entirely, people change with time. I scammed back in the day and, with time, grew to see the error of my ways, make amends etc. He may change for the better, he may not. Currently he's a delinquent who has a gambling issue, is in debt and has shown a lack of character. Only time will tell what will happen in the future, I hope he takes steps towards remedying the situation when he is able to and has decided it is the right thing to do.
Long story short, the decision making process can't be pinned to simply one factor alone. Temperament, personality, interests, stressors, age, experiences and more all combine in an ugly manifestation for one to decide to steal from another. What's truly alarming is that it's so common not only on this site but throughout life.