Honestly, you just roll with it. There is an inherent amount of luck in Dominion. Play enough games and things will even out.
Things like Swindler hitting Copper instead of Estate, getting a 4 Cultist stack to empty the ruins a turn before your opponent, Sea Hagging your opponents Sea Hag, unsupported Turn 5 Treasure Map Collision, Chapel turning up on Turn 5, Opponent getting KC/Mountebank before you, etc...
I could continue this list for the rest of the afternoon. The point is, there is luck in Dominion. Yeah, Tournament is certainly a large culprit but it is not the only culprit. As Adam Horton would say, "You make your own shuffle luck." While that phrase may sound catchy, I would say that you respond to your own shuffle luck. Regardless of what your deck draws you, you can always play a game in such a manner that you maximize your chances of winning. Some games, that percentage is really low due to uncontrollable circumstances but in a lot of games you can still play to the best of your ability and some combination of your own luck or opponents play can bring you back into a game. However you might only get that chance if you take the misfortune in stride and still play your best.