"Never loan anything you hope to get back."
Those words of advice, given to me by my father and echoed by several friends during the past decades, have turned out to be remarkably true.
I was looking over the list of people who have borrowed significant sums of money (triple digits or above, in fact) or significantly valuable items from me during my life, and I came to the surprising realization that in the past thirty years, only four people have thus far fully returned what was loaned.
Most have made only the most token of efforts to repay anything at all; two have even told me, "Well, you make more than me, so you can afford to do without the money more than I can," as if my willingness to help them at a moment of financial need was a duty on my part and not an attempt to assist.
Bearing Dad's advice in mind, I can't say I'm wholly surprised by this realization--but it's still surprising when I realize how many people who still owe me have no trouble coming with funds for other non-necessity expenses, but can't be bothered to make payments on their debts.
In some ways, I view it as a test of integrity; if I borrow from anything from a friend, I make a point of getting it back to them. If I borrow a book, I return it; if I damage it, I buy them a better copy. If I borrow money, I repay it without asking.
I'm still a little surprised by how few people operate the same way.