Forums let you hide behind a virtual character. Some people gain pleasure from making others think they've done this, or that. Everyone lies about their achievements anyway.
Speak with someone about the number of chicks they've bonked, and chances are they're exaggerating the numbers by 30% or 50% (or whatever, but you see what I mean).
There's going to be a time when you too will say something on a forum which is not quite true, I know I do it. But I don't bullsh1t about my car, the cars I've driven, or my computer. I don't think it's appropriate, and many, many people on other forums know me personally, so they could quickly call my bullsh1t out
That's human life, we all want to be better then the next person.