As a smoker, my two thoughts are:
1.) I'd rather have a 10% chance of dying than a 10% chance of living many years with something like Alzheimer's.
2.) I'm not someone who says "I wish I could quit but I'm addicted", I find it easy not to smoke but I do it because I really enjoy smoking. I'm trading possible early death with current pleasure. Alzheimer's doesn't have any upside or choice involved.