According to the CDC, 80-90% of lung cancer deaths are linked to cigarette smoking (1). It seems like a simple solution for people to just not smoke...
'Nicotine releases a chemical called dopamine in the same regions of the brain as other addictive drugs. It causes mood-altering changes that make the person temporarily feel good. Inhaled smoke delivers nicotine to the brain within 20 seconds, which makes it very addictive—comparable to opioids, alcohol and cocaine. This "rush" is a major part of the addictive process.
'When the person stops using tobacco, nicotine levels in the brain drop. This change triggers processes that contribute to the cycle of cravings and urges that maintains addiction. Long-term changes in the brain caused by continued nicotine exposure result in nicotine dependence, and attempts to stop cause withdrawal symptoms that are relieved with renewed tobacco use.'
Same for lots of dependence causing substances, effects are greatly varied by delivery mechanism. Eg heroin pills used to be quite common over the counter and weren't considered a hard drug.
'When the person stops using tobacco, nicotine levels in the brain drop. This change triggers processes that contribute to the cycle of cravings and urges that maintains addiction. Long-term changes in the brain caused by continued nicotine exposure result in nicotine dependence, and attempts to stop cause withdrawal symptoms that are relieved with renewed tobacco use.'
https://www.camh.ca/en/health-info/mental-illness-and-addict...