I don't know who you are or what type of player you are. A good way to really shine the spotlight on yourself is by posting in the forums. I will try to answer most of your questions, IMO of course.
"Why is it that only the best most powerful players can win at those contests?"
-IMO raw activity, I have not seen very many donation based contests. They are the best for a reason, activity, and donations. Donations however, do not make the player, the player makes the donations. Two of the top 10 players have donataed a combined 5$.
"I couldnt have won that contest if I had played it all day."
-Pure luck to win contest, and a nice strategy could have helped you with the final blow.
"Why is it that the most powerful players bully the c**ppy players such as myself?"
-IMO you have done something to draw attention to yourself, either by forum posts, whining, or in-game mail, and also may be due to certain actions in-game. I haven't a clue, and am purely speculating.
"I tried to make some cash (about 14 grand) from credits, and since I wasnt able to put a deposit for them to be put as anonymous, the dude that bought them got half of his money back."
-You took the risk. You could have also used the other "no upfront cash option." Again, you took the risk and the other player broke no rules.
"Im really begining to resent this game..."
-That is your absolute right. It's slow in the beginning, my advice is to forge some relationships in-game... Shmooz some higher-leveled people into sticking up for you. This game is what you make of it. Hope I was able to help!
And nice to meet you