The answer is very simple: Because we like to do it...It's fun and offers (especially newbies) who enjoy writing, an opportunity to earn a little more REWARD here for their efforts.
Another thing that contest participation does for the community, is to provide another outlet for people to connect in a meaningful way.
The @averageoutsider initiative, is not totally altruistic in nature, but primarily the motivating force. You can easily find a host of scams, cons, greedy and otherwise nefarious tricksters operating on the steemit platform purely to 'take'. They make it a 'business' while pretending to have your interests, solely in mind.
AverageOutsider is here mostly to enjoy the platform with any monetary rewards of course appreciated, but considered secondary in nature...If you think that's weird...stupid or crazy...'I don't really care'
It's like Popeye used to say..."I am'z what I am'z, and that's all that I am'z..."
That's it for now...Enjoy your day.