Guys, let's slow down here for a moment and examine some of the "whys" and use some concrete examples. I have a few more thoughts and examples, but I need to get them organized. Nevertheless, let's look at some of the issues and see if we can't resolve them.
I recently played at Pine Valley with another member of my club here in Denver whom I hadn't met or played with before the trip. He is a very short hitting but consistent 13 handicapper. Playing from the next to back ("regular") tees as we all did, he struggled mightily on several holes at Pine Valley. For example, he couldn't hit driver far enough to be able to reach #2 in two or the fairway area of the par three fifth, and he couldn't carry the waste area on #16. Carrying Hell's Half Acre was a challenge unless he was up very close. During the first round, his caddy suggested that he consider moving up. After the round I suggested the same thing. I suggested it again after lunch as we headed to the tee for the second afternoon round. He didn't say anything and never moved up. I didn't know the guy well enough to get into his grill about it; I mentioned it to a couple others in our group who just shrugged. I'm not saying that this guy didn't enjoy himself at Pine Valley--I think he did. However, I think he would have enjoyed his experience there even more and still had all the challenges he needed if he had moved up one set of tees. Pine Valley is a surprisingly playable course off the tee if you can carry the ball far enough (and in most instances it's not that far). None of the rest of us would have given a damn. I learned afterward that he never plays from the back tees at our club, which aren't Pine Valley difficult by any stretch but also present some similar forced carries.
Why? As others have mentioned, ego, peer pressure (real or perceived, doesn't matter), machismo, maybe because one enjoys the nearly impossible challenge?
In the words of Clint Eastwood, "A man's got to know his limitations."
Harry Callahan: Well, I just work for the city, Briggs!
Lieutenant Briggs: So do I, longer than you, and I never had to take my gun out of its holster once. I'm proud of that.
Harry Callahan: Well, you're a good man, lieutenant. A good man always knows his limitations...
Ah the challenges and temptations of golf. Maybe it's why each of us is enjoys going "Tin Cup" from time to time (or all the time...).