@takahmamash When are most of these people starting to smoke? Are they mature 30 year olds? Or are they Teenagers who are more likely to be making stupid decisions.
You obviously are not a teen and don’t think like one. If you were to view how a teen thought you would see that they want to hang out with their friends and have something in common with them. Plus these people try to imitate the older bochrim who they see smoking and it gets in their head that its yeshivish to smoke.