One of the ways sub-optimal decisions show up is through the interference of real world events, relationships or scenarios.
A while back, I played a fantastic game of Settlers of Catan with my wife and mother-in-law. You can probably figure out where this story is going just with those two variables.
I would consider both of these people highly intelligent. And very strategic-minded opponents.
The first suboptimal decision I made was this: first turn of Settlers of Catan I decided to adopt a highly aggressive strategy of territorial expansion. I "felt" like roads were the way to go and blocking out a good area to build my civilization would enable me to get the settlements and cities in place faster than my competition.
This is the kind of decision you make when you have recently been playing against a lot of computer opponents. Computer AIs typically don't react to what you are doing except in a very abstract, calculating way.
What happens in real life is usually much different.
I had blocked off one of my wife's roads. She had wasted a wood and clay to build a road she could not continue because of my own encroaching road. It felt so good I did it again a couple turns later after she tried to expand another road.
So my territory was expanding.
But my public perception, the one in the minds of both of my opponents, was rapidly degenerating. Underneath the surface, I was becoming Public Enemy #1.
I was punished in the way that the leader is often punished in multiplayer games. I, who had been trying to do the blocking, was instead blocked. 1 civilization has no hope against 2 other civilizations working mostly in unison. My trading opportunities were eliminated.
But I was just doing what you are supposed to do to win, wasn't I?
No, I wasn't. Because I didn't win. My wife won. She was able to gain positive support by being the underdog, and then used her own resources to their optimal effect.
I could have sat there and complained about everyone acting outside of their own best interests. But my wife was certainly trying her best. And my mother-in-law was reacting against the biggest threat she saw at the table…the guy who was apparently going for the throat. A game player all her life, she saw the warning signs I didn't realize I was putting out.
About a year ago, I derided the lack of player interaction in most Eurogames. But this scenario is exactly why people avoid conflict so fervently. You can't just built a machine of winning and let it go to work. You have to feel out your opponents and also see how they you.