There is more to Brazilian jiu jitsu than jiu jitsu, and brazilians for that matter. Character is important, and I think the training itself is a powerfull filter for those with the wrong sort of character. And I guess thats why you get so many guys and girls from different backgrounds but who get on well in the training environment, because of the similar traits needed. Ive often heard of this also being a sort of prequisite for promotion within the art. Even with boatloads of ability you will not get far if you dont treat your training partners well, respect your instructer and dedicate yourself.
I think club compatriots invest alot of time, effort and emotion into each other. Things we cannot afford to give everyone, and definitely not those who have shown themselves not to deserve it. Im not just talking about the guy who slams you to escape the triangle, Im talking about the guy who ignores the struggling white belt or refuses to help get a guy ready for a big fight or comp. The guy who only fights those 10kg lighter and then makes excuses when he gets put with a bigger guy. The guy who demands his instructer promotes him or he will go elsewhere.
Luckily I dont see those guys very often, they dont last. And the ones that do have a very lonely road.