So say it's repeated. Since our observable universe will end someday, there will come a time when the probability of future flips is too low to justify paying if the coin lands tails. Your argument suggests you won't pay, and by assumption Omega knows you won't pay. But then on the previous trial you have no incentive to pay, since you can't fool Omega about your future behavior. This makes it seem like non-payment propagates backward, and you miss out on the whole sequence.