Honestly if you haven't learned "do not try to defraud people out of their money" by 22 I doubt a few more years is going to change his mind. Furthermore by 22 the vast majority of people are able to lead healthy adult lives without scamming people. They don't have the experience that older people do but it shouldn't take a lot of experience to know that stealing from others is wrong.

I also don't think Christian did the scammer a favor either. If anything Christian's interaction with the scammer may have emboldened him because even when he got caught he got away with nothing lost other than a potential reputation hit with his family. Can encouraging a known scammer to keep scamming by showing them how to not get caught and that there aren't any consequences if you do manage to get caught really be considered a favor?

Stop infantilizing people. People don't become proper adults until they've had a few years making decisions and handling the consequences. If you just keep giving people easy outs and rationalizing it as them being young and stupid they will never become smart. Yeah, some people are gonna have to go to jail for their screw ups but on a societal level that's preferable to everybody still acting like idiots at 25.