I will agree that addiction is a very powerful thing and can affect people in many ways. Still, often when it comes to drugs (and alcohol) and no matter if we are talking occasional recreational usage or addictions, I personally tend to think they just pronounce or enhance certain traits that are already there within you. Lots of people do stupid immoral things while on benzo + alcohol for example whereas I have never harmed anyone in any way and I know there are many others like me. I don't think that's just a matter of biochemistry or how a particular individual reacts to a drug - I also think it has a lot to do with who you are, your morals and personal beliefs. If you're not inclined to get violent or do stupid things while sober it is probably much less likely that you will react that way when intoxicated.