A distinction: at one point you said Murphy Chan acted cruelly for "no reason," which is different than unnecessarily or for no gain.
He had a reason in the sense that something motivated him. Maybe in the past that strategy achieved the results he wanted, maybe he was trying to emulate someone else who succeeded with that strategy, ... I don't know. But I know something motivated him.
I distinguish having a reason -- that is, knowing someone's motivation -- from necessity or gain because the better I know someone's motivations the better I can influence them -- whether to disrupt, negotiate, pacify, or whatever.