I feel your pain. I've had many games where my opponent has Sea Hagged my Sea Hag on Turn 3, or Swindled my opening buy, or bought the only trasher in the kingdom in the Black Market or got a far more favorable shuffle with their Familiars than I did. But, I can not control it, and, like anything in your real life, you shouldn't worry about the things you can't control. The key is, as everyone here as indicated, to minimize the amount of luck you need to succeed, and better control the things that you can. Losing repeatedly due to your opponents' "luck" should only motivate this further. Take a look at every game that frustrated you, and see what could have been done differently. Take notes, especially on the different card combination used against you.
This is a game against Celicath recently where I came within a turn of winning, had he not had enough to buy the last Province. Did he get a good draw? Yes. But did I play this game perfectly? No. I should have taken a Duchy on the previous turn instead, among other things. He would not have had enough money to buy the last Province, and then I would have on the next turn. I'm far more concerned about that mistake than I am the fact that he got "lucky" enough to win.
http://councilroom.com/game?game_id=game-20110709-184204-ff01870f.htmlThere will be "Are you f'ing kidding me?" moments in almost every game. Armando Gallaraga didn't quit baseball after Jim Joyce took away his perfect game. Players in the World Series of Poker still come back after their opponent gets a break they only had a 1.4% chance of getting. Are these the same as a bad draw in Dominion? No, but they're the out-of-control aspects of these games that the participants simply can not do anything about but keep going. These are the things that makes these games what they are. You could not possibly have Dominion as it is without some luck factor.