Triple Triad is for fun. All should have fun. Give ALL a good reward for participating and the best something more. Not 1k -> 140k and a priceless card. More like 2k -> 10k. People should have fun, not begin to hate each other over it...

It's too important whom you play than how. 15 games, over. "Oops, so I won my games (and with the plus rule, EVERY match is a risk), but got only (f.e.)1250 points, because I somehow played against the wrong people? And how should I know that? And why can't I do more games, fighting the stronger people, so I still get a chance? I didn't lose any - so why did I lose?!"

In addition, if you allow them to fight against stronger people (and maybe you could create a title, which displays their actual points for this week?) to climb up the ladder, the tournament will go on for the whole week. And when you give everyone a nice gift for participating and the winners just a bit more and not the big jackpot, this all will be handled much more civilized.