pizzapie,
While I can't talk from personal experience regarding the so-called typical addictions like alcohol and drugs, I think that I can offer some insight. Ihave an addiction to food, or the over consumption of food.
Many years ago, my dad, who struggled greatly with alcohol addiction, decided to look into something to replace his vodka cravings. Back in the 1970s . Dad, a devout Catholic who was in his mid 50s, decided that perhaps he'd like to find something else other than alcohol, so he tried marijuana for the first time. But it didn't seem to bring him the enjoyment or pleasure that he was hoping for. (Thank God!)
So, to answer your question. I think that folks can switch from one addiction to another. It's good that your were aware of that possibility.