Logic doesn't need to have anything to do with it. As much as some people may dislike this, it's not the only thing in the world. Opinions can, and often are, entirely baseless. For instance, I am totally pro-sobriety. I really value being sober, and I appreciate other people who are sober, and always have been sober.
Why? I'unno. It just feels more 'right' to me, and someone might come in with some explanation about how it's all about legality this, and image that, and some other thing. For me, I just feel like being sober is right.
As for how that puts me with pot, it actually is the reason I resent it more than more addictive substances. With more addictive substances, you've got more of a biochemical reason (or something like that) to be compelled to take the drug. I know... personally, no smokers who want to keep smoking. I also appreciate willpower, yes, but I'm more ready to forgive the person who can pull out a doctor's note written beside some x-ray of their brain that says they are technically addicted to something, *inhales* than someone who repeatedly leaves sobriety by choice which is in almost no visible way connected to addiction.
This also makes me dislike people who drink only a bit. They're not addicts, they just drink. Yes, I actually have more leniency with the addicts, because they're more excusable to me. That being said, if it's a choice between the two, don't care about what I say, less of this stuff is always better than all of it.
Point is, all those people who aren't addicted to something they're doing could totally not be doing it. This is different escapism than reading, video games, movies, or other entertainment media. Those things put you into a different state of mind, but you're still sober. And besides, that entertainment is (read: 'should be') a compelling piece of media that rewards your attention with information, or thought-provoking questions and a new outlook on things.
That's how I feel about it, and I really don't want to offend anyone, and I'd like to think I'm not important enough to. No, I'm gonna try for "important enough for the OP to read and maybe consider". Solid goal. But no matter what logical fallacy my argument may hold, or how prehistoric my feelings may be, they're part of me, and they're what I value, and I wouldn't be myself without them.