There is a lot of emphasis on Harry becoming the wielder of the Elder Wand once he defeats Draco. However, how do we consider when one is "defeated"? Basically, Harry and Draco have a wrestling match and Harry wins. So now Harry is considered to be the master of the Elder Wand. Yet, after this event, doesn't Harry get "defeated" by the snake, by the Snatchers, and even by Volermort in the forest? Why aren't any of these considered as "defeats"?
The snake almost kills Harry. Harry escapes just in time but his wand breaks. The snatchers chase Harry (and friends) through the forest. Harry and friends basically give up (and Hermione has to even change the appearance of Harry's face). Voldemort almost kills Harry in the forest (or actually does depending on how you look at it). Why aren't any of these considered to be "defeats"?