Drugs and gambling are very different from each other but they are also same because it is both addicting. "gambling addiction mainly due to loneliness and dissatisfaction?" No I dont think so. As of my experience we become addicted to gambling because we become greed and we become tempted of this thing. We want to win the big price. Gambling is money. Money is temptation.
Loneliness and dissatisfaction are just two states of the mind, but this does not mean they simply will always be the cause of an addiction and that does not mean they cannot.
There is something about life, one thing usually lead to another and from there, you may even find yourself getting addicted by thinking you can find solace in gambling as a result of loneliness or some form of dissatisfaction on certain things, while thinking that you will just simply get out from it because of gambling. That is more like moving from frying pan into fire and that mindset you are bringing already can take you through the wrong path if you are not careful.