Well, in some cases, a guy walks into a bar.

In other cases, a still-single, 35-yr-old, financially-successful, socially-awkward douche bag walks into a night club and as a way to get the attention of the 22-yr-old, equally single, equally insecure, equally shallow women inside flashes his black Amex to prove that he's got $$.

Or maybe earlier in the evening, that same douche bag, who perhaps doesn't really have as much money as he wants people to think he does, is picking up drinks/dinner/etc. at a business function and wants the rest of the guys around to think he's a "big shot". I remember dealing with these when working in entertainment - guys who had black cards but didn't realize that the benefits were pretty worthless when they flew coach and could only get hotel rooms with two double beds since company partners would often share rooms...