When one takes out a loan, it's basically borrowing from all the others. It is somewhat cannibalistic to encourage people to do that for frivolous reasons.
Not necessarily, credit unions can trade money/loans like any other bank.
They can buy and sell securities that include loans made by other institutions. They can also sell loans that they write. Neither of those activities is predatory at all. Nor is the fact that they can only sell loans to people who have accounts there and who are by definition shareholders of their company.
However, when an institution tries to deliberately inveigle its shareholders into borrowing money for a frivolous purpose, I call it not just predatory but cannibalistic.
If a bank were to make the same pitch to its customers, encouraging them to borrow so as to spend frivolously and get into debt, it's just a bank being its usual predatory self. We expect banks to act in the interest of the shareholders, and we recognize that because although some of a bank's customers most likely do hold shares in the bank, most do not. Owning shares in the bank isn't a necessary precondition of doing business with it.
With a credit union, the only way to get a loan from it is to be a member, and hence a shareholder. So the pitch described by the original poster boils down to: "you've bought shares in this company, so we're rewarding you for that by pressuring you to sign up for predatory loans that benefit other shareholders including you". It's an extra level of sick. Any shareholder who falls for it is doing the financial equivalent of chopping off, grilling, and eating their own foot when they have perfectly good food in their refrigerator.