its not just about tolerating pain, in fact id say thats a small part of it...and actually its fairly rude and insulting to imply that your fellow runners somehow wanted the victory less or weren't trying as hard..
'guts' can also mean having the confidence to take a 2 mile race out in 4:01, being willing to lead most of the race, and having the confidence to kick at the right time and take control...
guts is mainly being aggressive/bold enough to make moves when they need to be made, and not second guessing your efforts
that being said, its not ALL about guts...Alan Webb had alot of guts a few years ago when he dropped that 12 second 100 in the WC 1500m finals, with 700 meters to go, while it was gutsy it was also dumb..