It seems he made most of his money off his own people, the Jews. He cultivated relationships with Palm Beach and Long Island society and used his contacts at Yeshiva university to get to the money. Several Jewish charities are now going out of business because they had entrusted him with their endowments, which are now gone.
Overall a very strange case, but it brings us back to the maxims:
- If it sounds too good to be true, it probably is.
- Don't put all your eggs in one basket.