Caffeine is a powerful drug that is overlooked by many of us.
Like nicotine many people are addicted to it.
Caffeine isn't necessarily bad, in the right doses it has been observed to be great for our health, but if your drinking 8 cups of coffee a day to keep yourself awake you probably have some kind of underlying problem that will eventually catch up to you (stress, long hours of work, not enough sleep, poor diet, chronic illness etc.).
Smokers can try to rationalise their addiction all they want ("there isn't enough evidence about the health effects"..."I don't care"..."meh!"...etc.) but in the end of the day they are slaves to nicotine. If they don't get their regular hit of nicotine - they lose their marbles...junkie mentality.
I guess it is caffeine and nicotine that seem to suit the turning of the wheels of the political machines of industrial market economies if you ask me...imagine if people turned up to their 9-to-5 jobs half-awake...certain business people would not be happy about lost productivity.