One must endure the unpleasant situation that they have created. A shortened version of "(one) has made (one's) (own) bed and (one) will have to lie in it" (and all similar variations). I don't feel at all bad that he has no friends after having sold everyone out on his way to the top. He made his own bed. It really sucks that I lost my job because of what happened, but I guess I made my own bed.