You are right and your son is also right. As a father of sons I share your concerns and I hope that I'm able to give them the capability to withstand that peer pressure. I've been - and still am - subject to this on account of not drinking alcohol, smoking or using drugs. To the point that it becomes ridiculous ('don't be boring'). This has been a recurring thing since my teenage years and I really don't get why people feel the need to pressure others into joining them in their stupidity. Just like I don't push them to behave like I do.

But it's been tough, on occasion and I can see the point that your son makes, and I hope with you that if that day comes that he will remember it. FWIW you can tell him this internet stranger agrees with his dad and that peer pressure can be overcome.