Agreed but you're missing the point, which is that the individual might have so believed in Kubrik's art that he wanted to make personal sacrifices in pursuit of that. For all we know (and others undoubtedly know more about the story than I do), this man might have actually been in love Kubrik and wanted nothing more than to be close to what he perceived as "greatness."
I'm not even saying whether I think it's morally right or wrong. Only that it's not hard to imagine the scenario.
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.
I'm not even saying whether I think it's morally right or wrong. Only that it's not hard to imagine the scenario.