He knows that had he been able to eat a steak before the fight, the outcome would have been different. Because he has already taken out credit on the loser's share of the purse, he leaves the fight penniless and in despair.
He understands that if he had been allowed to eat a steak prior to the fight, the consequences would have been different. Having already incurred debt by taking out credit for the loser's portion of the purse, he exits the arena in a state of financial ruin and emotional distress.