Oftentimes in a big game of Settlers of Catan (4 or more players) it comes down to two or three players battling for the winning point and one or two players who have too few points to offer any realistic chance of victory.
Rather than just watch, the losing players are free to make overly generous trades to control who wins in a weird inversion of control.
Is this a natural side effect of the games? Is this just a manifestation of be nice to people on the way up?
I find this really frustrating as more than once I've ended up losing because I've annoyed someone in a previous game. I'm I just being a poor sport?
The only way I can think to avoid this style of play is to run a league setup such than even if a player isn't going to win, it's worth them trying to get an extra few more points.