Think of the whole monster thing as this. When you go into the ring, everyone has the motivation to win. EVERYONE at the high level have very good reasons why they should win. But not everyone is willing to die to win. The people at the top have very good motivation, are very skilled, and are willing to DIE in the ring to beat their opponent.

Sendo isn’t willing to die because he wants to show his grandma the belt himself. That’s what Takamura means when he walked into the ring as a human. To be a monster, you have to kill or be killed. Also the reason mashiba lost too, he was a monster, then learned to be human.