I gotta ask, Is he really good at making you feel guilty like you are a bad mom? If so, don't let him. Kids can be manipulative.
On the other hand, kids are going to have to make choices about what they are going to do in a "free" society. Why not make sure he understands that? Lots and lots of things aren't a great idea. Drinking til you puke, not a great idea! Sorry for those that like it but smoking anything or other things, not a great idea. Waste of time and money.
Time and money are important. Spend your money on a car or a nice house or memories [like vacations that are awesome] that last a lifetime not cigs, combustibles or booze. A drink once in a while won't hurt you but anything more than that is just
throwing your time and your money down the drain. Give out some guidance.