All of those.
A ruler need not be corrupted to be improvident or unwise:
1. My wicked uncle disagreed with me on policy, and now is intriguing against me. If only I could afford a bigger army...
2. My beloved daughter has been struck down by illness, and all the doctors in the land have proved useless. I wonder if a foreign doctor might be brought from far away...
3. My people have been devastated by famine or flood. I have emptied my coffers and opened my forests to hunting, but I wish I could do more...
Usurers: "Say the words, Goy!"
Ruler: "I would do anything...!"
Usurers: "He said it!"
Usurers: "Your Majesty, our sincerest and most fulsome commiserations on your predicament.
I'm sure you have heard many bad things about us, but it is slander and lies: we feel and understand misfortune very well. Very well, indeed."
Now we can help you, but we can't just give you the help, we have our little traditions, and you must accept that. Sign this contract, and all that you wish may be commanded..."