you can tell a person has sunken into his gambling vices if he has already done crimes like that grandpa who kidnapped a kid for ransom. it's probably not his first, he must have stolen lots before this like jewelry or so. it can be hard for this old dog to stop gambling as he is addicted. even in prison, he will still gamble that's for sure.
hard for someone to resist when he has money and can easily access a platform gamble. he doesn't just need community support but things to get busy about.
You are correct before committing such a henious crime this grandpa might have committed others which never came out in public. That is what chronic addicts do and since he was not caught previously he thought this time too he will walk away with this crime. Old man got overconfident and now will rot in jail for this crime.