It’s a version of both these things. They are pre-selected from a group who sees themselves as ‘us against everyone else’. There is an old notion that basically says “If you want to unify your country, find an enemy and start a war”. When your enemy is ‘everyone except us’, and you proceed to act on that basis/be attacked on that basis, it tends to really motivate and empower your group. (see Israel)
If your group has a mindset of “us against everyone else”, and you have leadership who is competent enough to manage that group, use them effectively, give them something to participate in and rewards for doing so, then you’ve just created a cohesive community, using their power effectively, who are being well rewarded for doing so, and are not suffering any major harmful consequence as a result. Wars, crusades and power blocs through history have been fueled by just such factors.
Once that momentum is established, you get ‘everyone loves a winner’ (well except the people losing to them of course), and people start looking for ways to sign up. Although they originally recruited from their own forums and pre-established group, after things began to require greater numbers, they set up sister fleets to act as gateways and allies.
Karmafleet: Come join Goonswarm
I believe that in essence the “trust problem” was mostly solved by keeping high-level access among ‘true goons’ with numerous relationships within the Goon community. The lower level recruiting provides the benefits of Goonswarm to the broader alliance, without exposing the higher levels of control to un-vetted members.
The lesson to be learned is pretty clear. If you want to retain players/members, give them a focus of action, make them feel empowered in doing it, reward them for doing it, make them feel like they are on the ‘winning’ side, and minimize the amount of time they spend feeling like someone else’s victim.