what these events do is give you a focus and meaning/motivation to go the extra; to train and get fit.
to get a sense of achievement and in the end this can simply makes you happy (ier) as we know how much fun mountain biking is. !!! its all about fun, ego is secondary, when I race in these events my main competitor is myself.
otherwise we go through life, wish I did that, can't do that, too fricken old to do that whatever - no time etc. I have plenty of mates in that position.
I've got 3 kids, I commute and take in single track as training, if I can't get out for a ride I get on the rollers .... do it indoors, go night rides, whatever it takes to achieve my goal of 8-10 hours training a week.
Why do all this I hear you ask? Well our jobs are sedentary, a majority of Aussies are slobs and will probably enter the health system early due to lifestyle diseases like diabetes, heart disease etc. We have kids that look up to us as role models so we need to be examples of being fit and healthy both mentally and physically.
So really whatever makes you happy, I'll be smiling when I cross the line.