I’ve been told that they run the organisation as a charity and purchase as much as they can through group or company discounts. Mortgages are arranged internally, being loaned by the senior members. They have a purchasing arm which, for instance, bulk buy VWs which are used by members.
They have lots of business interests which fly under the radar because ‘they keep themselves to themselves’.
They dont believe in education after a certain age (16?) so their schools are staffed by non-members. (My friend is one of these.)
I found out last year that a uni friend’s family were brethren. When he divorced and started seeing another woman he was cut off entirely by his family.
The split between Exclusive and Plymouth Brethren is worth looking into if you like a bit of hypocrisy.