It wasn't a suckers bet, it was a bet between FBGs. You count on them and expect them to be honorable about bets. Especially established FBGs.
No there weren't any black and white stipulations, there was just simple message board trust that both parties involved in each bet would do the right thing at the appropriate time.
When Tiger officially retires, that will be the obvious delineating point to pay off the bets.
Could Tiger come back and play again in the future after he retires? That would be exceptionally unlikely, but sure it could happen.
If that did happen, and by some amazing turn of events Tiger actually went on to break The Gold Bear's record, then you'd count on the previous bet "winner" to turn around and pay back the money plus his side of the bet.
Oh well.