Because A. You aren't fast enough, or B. You get repeatedly 2002'ed to the point where the grace period to reenter the queue with your spot expires. I myself got 2002'ed at 621 in the queue earlier, logged right back in and I was still in my 621 spot when I queue'd again. A system is in place to save your spot, it's just that repeated errors can still screw you, or again, you aren't fast enough logging back in.
Also, to the OP of this thread: You want money back for something you didn't pay for..? You got the early access as a free bonus, there is no money to be had back. You can always try to refund the entire expansion if you're truly that angry though.
