Your neurology determines how addictive you are to alcohol or any addictive substance. The 'weak' (as you put it) MUST actually be stronger than those who aren't afflicted. It requires much more will power and inner strength to abstain for someone who is predisposed to this illness than not. All addictions are illnesses. Addictions manifest themselves from genetic variances. For the most part, those who are forced to deal with their demons (by no choice of their own) are almost destined to abuse substances.
Our biology, chemistry and neurology drive our social behaviors. Instinctual needs brought on by our physical state precede all our social manifestations. Your body is hungry; thus, you eat. You bowels need some movement; hence, you find a toilet. Social conduct and behavior are the end points of your bodies need.
Occasionally, it is a break down in adherence to social norms, but for the vast majority of sufferers, it is driven by their need to chronically self-medicate. Essentially, THAT is what is taking place. Substances are used in lieu of medicines to tamp down feelings which are not present in those who do not posses addictive urges.
Why would you even bother bringing facts into this forum?