I knew the CFI fairly well. It does not surprise me that he stacked the risks given the people on board and the evening in Vegas. He has always pushed the limits when it comes to making posh friends.
Personally, I wouldn't have flown with him in daylight in flat terrain, and am a bit surprised it took as long as it did for him to have an incident. I have quite a few pilot friends and would happily fly with any of them, but I always wondered how the CFI even got his license.
Still very sad. But probably very preventable for most GA pilots.