Honestly, if I had to play golf to get through my social interactions I would cheat my ass off (while laughing about it). Because, like OJ, I'm terrible at golf, and I'd just be trying to get on to the next hole and not hold up the group. Sportsmanship? This dude is here because he was a professional sportsman! A typical round of golf is just something to do to pass the time with friends. When these things involve sports or games, and one person isn't very good, you give that person a leg up or take it easy on them, if you're decent. Apparently OJ's rich friends cared more about some mythical honor code of golf than being a good friend, which probably reflects more on them than on him. If he was displaying some kind of character flaw by trying to charm his way through stuff he wasn't great at, this would be a common character flaw that doesn't hold the secret key to his becoming abusive, and then a murderer.
The “secret” key to OJ becoming abusive, and then a murderer, is that he always regarded Nicole more as property (as a symbol of his success and status) than as an actual person. This attitude was obvious from direct quotes that the documentary showed, but did not (in the parts I saw) connect to an assessment of his attitudes or character. He abused her for years, covering it up through connections to police and media, before murdering her. The documentary did cover this, but didn't (as far as I saw) connect it to familiar patterns of domestic abuse or the tacit agreements that keep abuse covered up. If there's one thing that's directly tied to his crimes, and also reflects back on American culture, it's these things.