That said, yes, Christopher McCandless did indeed do something extremely stupid, just to try to prove something to himself. He was utterly underprepared. That was, partly, his own choice; he didn't want to rely too much on 'civilization' or 'society' where everything is hashed out beforehand.
The movie isn't really that bad, and Hollywood gave this story about a man looking to escape society an alluring sheen of glamour. If that inspires people to do stupid things, then certainly don't watch Jackass or any other movie where people do stupid things for stupid reasons.
He would have made it past the river if he had simply brought a map, because a bridge was literally just a couple miles south of where he got stranded.
Now that's the one Adam Sandler movie I'd actually enjoy watching, just for the long protracted death scene at the end.
https://www.washingtonpost.com/news/morning-mix/wp/2015/04/2...