I know where you're coming from, and I purposely steered clear of any suggestion that you shouldn't be able to criticize us big-mouth masters guys (especially given that I've been known to predict a little myself! ... ;-) when we come up with predictions on these threads.
Hey, you open up your mouth in public, you can't expect not to hear a little back - no matter how it turns out.
That said, I think we masters tend to talk out loud on these message boards a little bit (though usually only on our masters threads) because for many of us, the other guys/gals on the threads are people we see and race against quite often. They're friends whom we go out to dinner with before and after races, have drinks with a few times a year, etc. So it's sort of like just sitting around with the guys/gals and throwing out your goals - the same as I did earlier today over the phone with letsrun poster Shorter Than Frank. On these boards, over the phone, by email - there isn't that much difference to a lot of us (I've been known to use all three to carry on a conversation over the course of a day). Even the posters I've never met, I consider them friends. I root for them. I sweat out their injuries with them. I cross my fingers that their training and racing goes well.
Also, it's not like when we were younger. There's no pecking order at these races based on time. When Tony busts a fast one, we all cheer - and he still has to pay his part of the check at dinner. He runs slow ... well, maybe then someone will buy him a beer (or about 50 when his back went out at Clubs!). So it's not like he's trying to score points on anyone by predicting a fast time - because there are no points to win.
Anyway, I'm predicting all us masters guys get slower over the next couple years ... but I'm predicting most of us keep predicting we're just "that close" to bustin' another great race!