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"I start to wonder if the person may be bipolar and experiencing a manic episode."
...I would think that depends on how many thousands of dollars you have in the bank. It would be nuts to do this if you had no money to your name and were struggling to make ends meet, sure. But if you're got a high disposable income, or you know you can make it up with work, why not?
I haven't had the pleasure of meeting Stevie, and I know nothing about his financial situation. I suspect neither do you. Regardless, you could easily cover the cost of a last-minute LHR-NYC flight with three, four days of contracting (I should know, I used to freelance iOS in London). Doesn't seem quite so crazy when you frame it like that.
What I probably wouldn't do is throw around the idea that simply because somebody buys a ticket on a whim that makes them a manic depressive.