I would say it is for power, simple as that.
None of the gb are particularly educated and if they were out in "the world" they would have menial jobs or be on social security.
As the gb they have power over millions, and by keeping them dumb and poor they are not likely to rise up and say enough.
They do have money, as well as the value of the various properties witlesses have been bequesting them money, property and jewellery for years. I think it is pretty safe to say the organisation will last quite a while with the funds they have.

If you don't live on the edge you take up too much room