A couple random thoughts about chess and the movie. (I used to play quite a bit many years ago, some of it serious chess.)
I don't remember people staring at their opponent as they did in the movie, although we certainly did quick glance to see reactions.
Actually many players were more obnoxious than portrayed in the movie. (Some were very cool too though )
Replaying games (after tournament) in your head at night in bed was true for me.
Losing a tournament chess game is psychologically more difficult than losing in any other sport I have done (I haven't done wrestling or boxing, they might be tougher)
Tournament chess is much more cognitively, physically and emotionally difficult than competitive running.
It seems like as I got older it was harder to play top chess than to keep running at a higher level. (That is probably very subjective but it was just a feeling I had.)
On a pick up game, the person who arranges their pieces on the board the quickest usually wins (assuming its not intentional).
I guess as in any sport, motivation, confidence and unwillingness to lose are everything in this sport.
Playing with a friend, competitive chess, and having both of you getting pushed to your limits, is an amazing experience. Win or lose, its an experience you wouldn't have had without your partner. Great to go over games afterwards with them to see what they were thinking.