I think that Epicurus might have invented the concept of F*** You Money (FUM). The popular definition of FUM is the amount of money that you need so that you are not beholden to anyone for your financial well being (not a boss, not a client, not a parent...). It seem that PDs 6, 7, 10, 13, 39, and 40 refer directly or indirectly to the FUM concept. I view the concept of "protection from other men," as perhaps an ancient equivalent of FUM. Interestingly, in PD 15, Epicurus says, "The wealth required by nature is limited and is easy to procure; but the wealth required by vain ideals extends to infinity." In other words, the less you need to be satisfied the lower your FU number.
On a personal note, achieving FUM has been a guiding principal throughout my adult life. I had arrived at a core belief that aligns very closely to PD 39: "The man who best knows how to meet external threats makes into one family all the creatures he can; and those he can not, he at any rate does not treat as aliens; and where he finds even this impossible, he avoids all dealings, and, so far as is advantageous, excludes them from his life."
I would be very interested to hear anyone's thoughts on this concept.