Hmmm. You bring up a good question, OP. I've know many folks who quit drinking after "sowing their wild oats" so to speak. I don't know, but it might be tempting for a young person to get to thinking they still have a lot of time before they need to quit drinking. While an older person may become more aware of just how numbered their days really are. Just a thought.
On the other hand some older folks might be more resistant to change.