I haven't tried joining the contest since I know that the competitors are really good and even If I have tried my best, I think I won't win any of the rewards there knowing that some of the competitors are repeated winners. We can't deny that they are a very good artist and they have an extra ordinary imagination about their art this is why we can't blame them that they are winning every time. I though before of entering the contest but after seeing the participants submitted arts, I know for myself that I have no chance against them. Though this still a good promotion for roobet since there still many who joins the artwork contest.
Some of the participants are repeated winners because their entries are really deserving to be on top.
But don't discourage yourself to try joining, you will never know how good you are until someone praise your art.
You just need confidence to try your luck too because what matter is you love what you're doing since it is your passion.