Would be nice if the GM policy of not getting involved in personal disputes was reworked at some point as this isn't even a case of stealing from the chest and running, but a situation where an entire group were being led to believe they were working for the benefit of the whole group when they were actually working to line the pockets of the one person at the top. Unfortunately that's also how the real world works. You won't likely be able to get much out of the GM as a third person, so your friend or someone else involved will need to contact a GM. Best you can do is blist the leader, he doesn't sound like someone you'd want to play with anyway.