You're opening another can of worms with that example. An adult, informed smoker that takes care to not cause second-hand smoking and that doesn't have any dependents, causes harm only to themselves. If they think that the reduction of stress or whatever else they gain at the tradeoff of their health is worth it, that's their choice. That's part of their bodily autonomy. As such, the tech is still not inherently bad.

You're conveniently dismissing a few concerns and from that drawing the conclusion it isn't inherently bad?