I think people dont want to place bets on this fight, because it might be sort of a disrespect to try to earn on such a matchup, when a young (yet not a real professional) is planning to beat an old man who is twice older. Because even if they bet and win, they wont be 100% happy that they won. People want Mike Tyson to win, yet betting on him is a high chance of loosing money. There is a dilemma between get happy and lose money, or get money and not be happy about it.