How is it possible that some smokers and drinkers live up to age 70, when others die by age 25?

Well, this is what's referred to as an if-then logical fallacy. The actual answer is, because there are plenty of other ways for people to die besides smoking and drinking.

it all depends on the person's genes, metabolism and other risk factors and various diseases that can cause death at an early age!

This is can be for a number of reasons some of which it is likely we do not yet fully understand but lets keep it to basics. 1.Genetics (if someone has a gene predisposing them to some conditions associated with the damage caused by smoking or alcohol consumption it may be a case of genetics loading the gun and the environment pulling the trigger. 2. Lifestyle factors, having protective factors such as a good diet, a lower stress lifestyle, adequate housing can help. 3. Healthcare, many people do not like being open about the extent of their problem with smoking or alcohol or feel that there unrelated health issues will be dismissed or seen as their fault if they do so, but being open regardless of whether you are ready to attempt to stop can mean that problems are identified and treated early upping the chance of a successful recovery. 4. The extent and moderation, many people do drink at least in the UK in excess of the recommened units of alcohol done over a long time in moderation this can cause problems but it is binge drinking that is more likely to cause immediate health risks and contribute to some early deaths. 5. Social support, at least with alcohol consumption not drinking alone can help to protect you from immediate complications as a ideally non drinking friend can identify when it is not for example a good idea to drive, with smoking they may also pick up on symptoms of a physical condition that you had not noticed.

Everyone's lifespan is different. Different things come into play when someone passes; chances are smoking/drinking weren't the only causes. It's my personal belief that you should live life to the fullest (within reason), because you never really know when your time will be. Drinking and smoking are okay within moderation.

Everyone person is different and this includes their bodies. Some people have smoked all their lives but is healthy and there are people who have smoked a few years and has gotten lung cancer. Nevertheless, one shouldn't risk this because you could be that person that gets sick from smoking and drinking. Everything should be taken in moderation, so, if you smoke and drink, do it in moderation.

There could be many reasons for this, from how much they drink and smoke, to their overall health and diet. Why do you ask?

It depends on ones immune system. The ones who lived up to 70 probably ate well and exercised enough to cover up.

Yes, the only impossible is certainty.

It depends on the person and how much they drink or smoke. When you're over-excessive like a pack of cigarettes a week, it damages your lungs much faster. That even goes for a drinker who drinks a pack of beer a week, it increases the damage to the liver. But people who only smoke a pack of cigarettes or a pack of beer a month don't damage the lungs or liver as harshly. It's still bad, but it's the intake that affects possible death. It'll still happen but intake affects it drastically.

Some smokers don't have an addiction to food or other harmful habits, smokers can sometimes be more positive about life incidentally. Everyone is loved by somebody, but sometimes people who take a far too serious approach to life won't be satisfied with it and make additional poor choices without considering the consequences.