I don't think gambling is a peer pressure type of thing personally. Gambling is very singular in that as an individual you either win or you don't and your friends being in or out have no effect. I mean I guess to a certain point everything is but overall I don't see this as a huge issue.
You made a good point and I would like to support this one. Sometimes pressure in gambling is something that we just build within ourselves and that is something that we should try to work on. Seeing our peers succeed or generate money in gambling does not really mean that we should do the same. Another thing is what we call conformity, we have this thinking that if our friend is doing this or that, we felt the need to follow them in attempt to fit in that particular group. Lastly, the catalyst that I really consider in gambling is the fear of missing out and sometimes we are consumed by it that's why we engaged into something that we don't really know that much about.
Even though the pressure is from within ourselves, it is found in almost every single human being. Whenever we see our friends doing something and succeeding in that, we tend to think that we should give it a try as well and we discuss this with our friends and ask them to help us in that venture as well. Now, if that thing is gambling, maybe we should set some limits for ourselves by only trying our luck and seeing if it works the same way for us as it is doing for our friends.
This way, we wouldn't get addicted to gambling and we can easily stop doing it if we see that it is not working out for us, and if we are sensible enough, we won't force it on ourselves but think that it is not important the exact same thing works for different people the same way, that's not how things work in life.