How about risking losing a chunk of one of only some of the statistics listed in the Top Players page in a gabling game, for gold. It can only be the categories that will suit. You cannot gain stats, just risk losing them... for gold.
So have some kind of system similar to roll the dice set up, where you can risk to lose and choose how many stat points you gamble. eg, your number of "games played", eg lets wager 10, gives you 1000 gold if you win, if you lose, you lose the 10 "games played", system takes random played games off you like you never played them, stats go down.
Wager amount: unlimited. Say, 100 gold for 1 stat
Lets make it a whole "cycle", if the player so chooses.
How much fun would it be to wager hundreds of hours of gameplay for masses of gold...