[Hikikomori]

You're missing the point, abuse is bad even if the abused accepts it for whatever reason. You can achieve great things without abusing people, it's not a requirement.

Your MMA example is also missing the imbalanced power dynamic that you usually have in an abusive relationship.

[voltaireodactyl]

The MMA market is a near monopoly. Ask the employees of the WWE (née WWF) whether that constitutes an abusive relationship.