It's their loss too. If there's only 8-12 of them then that's all the people they get to practice with.

You, in the meantime, get to practice with everyone else! Which is more than 8-12, I hope, plus any people you meet on courses etc.,

Besides, in real life you have no choice of who your assailant might be, so you should practice with a wide variety of people. And it's hardly likely to be a yudansha is it? So why are they practising solely amongs themselves? They're just losing out.

So, i agree with the others, just pay attention to your training and be courteous to everyone else including the frat.

All the best!