I shared an office with a young woman who bought a lot of stuff online she couldn't return (flash sales). One day I caught her staring at a Marni purse, which she wanted. She said very wistfully: "A purse like that says a lot about a person."
I laughed and said, "Yeah, it's says 'I'm stupid enough to waste all my money on a purse.'"
We got laid off at the same time. This was on a Friday, and she was taking a weekend trip to Paris. I told her, "this is great, now you can stay longer in Paris."
Her reply: "I can't, I'm broke."
The thing is, we both work in advertising and know how companies create desire for things you absolutely don't need.
The only thing I'll say about the Birkin bags is that auction houses are selling them now, some of them do increase in value . . . although I still would never buy one. :)