Gaming Groups come in various flavours and many gamers are members of multiple groups at the same time.
As your gaming evolves so does your group dynamic and I wanted to explore those a little here.
Established "Static" Group
This is often the group that people first find themselves in. Also referred to as the home group it is practically a closed shop to anyone else. Indeed when in this static group it is often the case that the members will only talk about the hobby with those other members.
RPGs, particularly long term campaigns do really well in these groups. Board and Card games also tend to be frequent past time. I also know of a few static groups of CCG players who use that group for deck testing and drafting to improve their knowledge and ability within the group whilst still gaming outside of that static set.
"Not A Group" Group
When is a group not a group? When it's a club or society of gamers who have managed to avoid the clique mentality. Within that club you are likely to find fluid groups but as a whole the club members aren't fixed into a subset population of gamers like the static group.
Clubs tend to increase the likelihood of greater variance of games which give gamers the opportunity to try something else.
Wargames tend to do really well in clubs but really all formats of tabletop gaming can co-exist within that "not a group" group environment.
Sort of where I am at the moment.
The fluid group differs from the static simply because the members are not fixed. What does that mean Dave? Well, the "not a group" may actually include a number of fluid groups within it.
If you play multiple formats of games then you may have different people that you play those games with and some of those people may crossover to different formats.
e.g. The group I am in for RPGs is fairly static although not completely but the group I'm in for Board/Card games is pretty fluid as it's largely just down to whoever is interested that night in playing games. The make up of the fluid group may be from a finite pool of people but at the same time the members will vary from session to session.
It's entirely possible to be a member of each of these at the same time and similarly you may only be a member of one of them. The key though is to recognise the benefits of being in the group(s) that you are in and understand the groups that you're not.
I'm not referring to the people within the groups (that'd be a far wider topic and verging on stereotyping) more that if you want to explore other formats of the tabletop hobby you have to recognise that the group you are in may not be the group you can explore that with. Similarly if you're looking to immerse yourself in a long term RPG campaign then that's really not that easy to do unless that group is static.