I think some people do fall into addiction more easily than others and go from one to another. But I think that once they are aware of this, they can guard against it and arm themselves with tools to beat addiction (finding the right psychologist is gold). The path to freedom from addiction may be harder, but it is still possible.
And there are some people who have a particular vulnerability and struggle with one addictive behaviour only.
I have seen people who fall into both categories. From my experience, finding a good psychologist who can help someone deal with their underlying issues and then give them tools for change makes a big difference to long term success.
I believe no one is beyond hope, and positive change is always possible as long as the person concerned truly wants it.
Gosh, sorry that was a bit longer than I meant to comment. I am no expert at all, that's just my observations from my experience with certain loved ones.