Regarding gaining entry - the masonic or scientology model is a good one - hierarchical, where each level up represents a deeper and deeper dive into the org. At level 1 its just networking and meeting interesting people and some membership dues. At level 2, you dues go up and you meet some more influential people. By level 3, maybe you'll be asked to do something in exchange for a favour - say, swing a contract or muddy someone's name. Now they have something on you, just a minor thing, but you're starting to get bound to them now. As the levels go up, more knowledge is received, more favours are given and more "commitment" is required in return, dirtier deeds or engaging in strange acts which will act to keep you loyal. By the time these people are deep in and sacrificing etc, they essentially ARE the establishment, they have huge power and they have committed huge sins and they know of the sins of others - as a result, each member has a very strong reason to stay loyal and protect the secrets of the others. It is a mexican standoff at the top, an atomic bond.

But this is all conjecture on my part.