They have neither the "right" nor the obligation, simply free markets and opportunity. An interesting statistic was recently announced on the news. 42% of people with less than a H.S education smoke. Around 24% of people with a college degree smoke occasionally. But only 7% of people with graduate degrees smoke. I look at the choice to smoke or not to smoke as the ultimate IQ test, now that the information about how it affects one's health is available.
For those who have started, it is indeed an insidious addictive habit, very hard to quit. A pack of cigarettes now costs more than a gallon of gas.
My Grandfather and my Father smoked nearly all their lives. My GFather died of Emphysema, a lung disease. My Father (who was a career military man) contracted Tuberculosis (which is not cause by smoking but can be affected by it) in the late 50's, had an operation, was in physical therapy for 18 months, and quit smoking for 8 years, cold turkey. But then he got assigned to a tour in Korea without the family for a year and came back smoking 2 packs a day. He died from complications of Emphysema, too.
Doctors say your lungs will recover from a history of smoking in about 6 years. Good for you!!