Lots of undiagnosed do all sorts of things to compensate, without even realizing it.

It’s called self-medicating. Some just do what makes them feel functional, some are aware there’s something amiss and pick the things that help them cope.

So if smoking helps someone, they’ll do it (and I suspect smoking is an effective mechanism).

That sounds like changing one addiction for another, so I’d advise watching out to not trap yourself in a dependance spiral.