By winning these contests you receive 0.50 mbtc in each table... it is very very easy for someone to play this amount in the meantime so it is not a real advantage that you can exploit.
it's probably a bug in the system but as mentioned I don't think it provides any kind of tangible advantage to the player who wins the contest nor any disadvantage compared to the other players participating
It is still "something", that should be the thing that you should focus on. I personally do not believe that people would ever complain about "free" money, just do what you normally do and in return you will be getting something in return and you will be profiting from it as well.
I know that it is not going to be something that would be beneficial for you in the sense that if you are gambling somewhere else, you wouldn't stop gambling there and start gambling here just because there is a small reward. However, if you are already gambling here then it could be a great thing that you could end up keep on gambling and be happy about the extra.