Facts have always been elusive things, tailored for a purpose and designed to benefit someone. Of course, "documentation" proves facts ... right?
The Black Book is strictly allegorical, IMO, describing a shadowy Organization that controls the resources, owns the law and steers politics from behind the scenes. Ike called them the Military Industrial Complex. Today I guess we call them the Deep State. Howk called them the KGC, although that group had played out by 1913 when the Organization took the catbird seat. I seriously doubt many folks believe Howk was being serious about all those "JJ identities", or was actually trying to be "factual" with the book.
Anyway, did some club of rich guys really put boatloads of gold back in the ground? Don't know, but when the value of the fiat US dollar goes to zero, we might find out. The dollar's already 98% of the way dead. My only question about the Black Book is, why did he write it? You could be right - just for the money. But book writers on that sales level seldom make any money or even break even.