Karzai Crazy?

So Afghan President Karzai has threaten to quit and join the Taliban. Big news. Big shock to the White House. Why is he acting so strange? Why would he do stuff to under mind NATO efforts and play right into the hands of the Taliban.

It couldn't possibly be that the US has given a date for when its leaving. At date after which he'll be on his own, surrounded by war lords, Taliban and the business as usual Afghan way.

I would assume that when NATO leaves they won't be taking him with them. So who can blame him. He's not in danger of being kicked out of office. He's in danger of being horribly maimed and killed.

So why is anyone surprised at how he's acting?