When you made this bet, what specific criteria did you think would constitute a win? A given age with fewer than a certain number of majors? I am guessing you didn't even contemplate such. You made a stupid bet without even thinking about the conditions that would actually grant you a victory.
I am not deriding you for making a stupid bet, as stuff happens. I would think that you do realize your mistake. But now you're acting like a spoiled, entitled brat expecting your opponent in the bet to acquiesce to some vague notion in your head of how the criteria should have been set.
Obviously Woods is a major underdog to catch Nicklaus. But it isn't impossible. People recover from injury. People come out of retirement. And we don't exactly have a great deal of historical data at our disposal to compute true odds. The number of people in the history of the world that won 14 majors by age 33 and then battled back and knee injuries along with spousal 9-irons to the face for the next several years is one.
I can't speak for Otis, but were I in his shoes I would be very close paying off had you not acted as you have. And that's probably not true anyway, as I am a softie and would probably pay you anyway.
But you don't deserve it. You deserve to be told to pound sand until Tiger dies with fewer than 18 majors.