Cheers to you, VaporClouds, and to all the great contributions on this thread. Thank you for your service - that doesn't even begin to express how much I mean it.
My dad was military, my son is military (I was too old by the time I figured out I SHOULD be military) - but it's true -- boundaries do NOT defend themselves, and freedom is not free.
I do not know why so many people seem to find an interest in messing with what other people are doing -- I really don't. Honestly, sorry, but I pretty much think it might be because they are too well-fed, too comfortable, and perhaps too bored, or unable, to figure out what's going on in their own lives.
So, along with all the other good ideas posted here about how to deal with intrusive, opinionated people who decide that YOU can be their next target ... it might be appropriate to say something like "seriously? do you not have something of your own to fix?"
It's along the lines of ... don't engage in conversation with crazy people unless you want to participate in craziness ... NOT that people who wonder about, don't know about, or might have a negative opinion about,
vaping are all "crazy" - but if they are going out of their way to address something YOU are doing, they might not have your best interests in mind, thus possibly negating the meat of the subject, it's truths, rights/wrongs, facts/fictions, etc. So it's kind of like "did you just want to assault me to pass the time (in which case, you're done), or do you honestly want to talk about this?" Appropriate conversations may follow...