Earlier quoted context omitted.
People inside our tight social circles are held accountable by social pressure. This is why, for instance, Mormons seldom defraud other Mormons -- it would make Sunday mornings unpleasant for a long time to come. That your uncle would choose very deliberately to alienate his entire family is the astonishing thing. Would be curious to know what his social life is like, now ...
Actually, "According to the FBI, affinity fraud crimes are especially prevalent in Utah." https://fox13now.com/2017/12/20/fbi-warns-lds-church-members...
So, yes, the farther away in the social network, the weaker the social pressure. If the link is mere nominal membership in the same faith, that may be worse than no link at all. Most of Madoff's victims were Jews -- because they were inclined to give him the benefit of any doubts.