I find that description "financially vulnerable" thought provoking. Just off the top of my head but I can't help but wonder if that has been and will continue to be a problem for siblings/cousins who are not heirs to the throne and don't have the financial security that goes with it. They grow up in palaces, go to the very best of schools, mix with the most wealthy and privileged, are called HRH but what in fact do they really inherit? They no doubt feel entitled to the best that life has to offer but can neither provide that themselves or receive it thanks to the taxpayers. They may live in some huge home but it takes a fortune to keep a place like that up. I am not excusing Andrew and Fergie's behaviour but can see where someone lacking in scruples would sell position, influence, their soul to the highest bidder and feel somewhat entitled to do so.
Well, the only current heirs to the throne with a reasonable chance to inherit it are William and Kate's kids. Andrew's in the line of succession but something really awful would have to happen for him to become King.
Andrew apparently has, or had, money that he inherited from his mother and grandmother. That has been his main income, along with whatever his brother has given him or not required him to pay, and whatever his mother gave him during her lifetime. But pretty much all of that is gone.
Fergie isn't from a titled family, but because her dad was a polo manager for the Royals, she was around them all the time when she was growing up. Most of whatever money she has is from Andrew or from shady financial deals. She netted almost nothing from her books and her other "ventures".
But the bigger issue is that for both of them, they want everything, and nothing is enough for them. Like when Fergie went on tours in the US to promote her kids' books, she demanded five-star hotels wherever she stayed. And she would come back with literally dozens of suitcases of clothes, furnishings, etc that she bought. That's ridiculous considering the number of copies that those books sold. She's not JK Rowling or Dav Pilkey.
They're both incredibly greedy and will do whatever they can to bring in cash. And they both have huge egos. Epstein saw both of those things, and exploited them.