How come it's a prison movie where people use cigarettes as currency, and it's set over more than 1 decade

It generally takes far more than one decade of smoking to get lung cancer and die. Also, the movie is not about smoking or cancer.

What a naive post lol. People have smoked for like 80 years before they croaked of something..

Leonard Nimoy smoked for more than twenty years, but didn't contract COPD until hos seventies. He died if it at age 83 after quitting in his sixties.

You only saw a small part of the prison population in the movie. There could have been dozens or hundreds of prisoners we never knew how they ended up.

SpiritualDipShit

Obviously, the OP did not understand the underlying message of the film and the reason it is so highly regarded. The movie's setting is a prison. I will not argue that. But the message is about "hope". And cigarettes in prison are like currency.