First mover advantage is good, but it is not the decisive factor, because others have a chance to improve their platform from first mover mistakes and successes. For example, Blockbuster was the place to rent movies, but before Netflix. Netflix delivered movies to your house at first, while Blockbuster wanted you to come to their store.
Steemit is risky, but I do like this reward system more than mining, because mining does not produce anything, and it spends a lot of power.