Luck

Although he wasn't totally aware of the complete extent of Taro's powers, M'Baku liked to believe that he's the one who knows the most. After all, he was the one who tailed him more than even the MIB officials. Even then, he couldn't blindly trust the claims that Taro made about how he was capable of destroying Earth. He thought of Taro's claims as someone spouting random bullshit. The more he thought on it, the more it seemed that Taro's claims were ridiculous.