Not smoking is the best thing to do for your health.
This year is the 50th anniversary of the Surgeon General’s proclamation that smoking is a serious health risk. As part of the commemoration the CDC is posting new health consequences of smoking and exposure to secondhand smoke.
Smoking is fundamentally negative savings. If you think of savings as current discomfort in exchange for future pleasure, then smoking is the opposite, it’s exchanging current pleasure for future pain.
The number of healthy years of life, your healthspan, is more important but harder to measure than your lifespan. You can’t blame people for doing things they don’t know are bad for them, but when they know better they should do better.