I seriously hope I have never been "that diver". But I think I have been seen that way. We did a week on a chartered sailboat several years ago. It was a group of eight friends, three of whom were literally just certified, and two more with a small number of dives. I did spend a fair bit of time doing some onboard coaching about buoyancy and gas management and stuff. It was all very friendly and well received, but it apparently aggravated the instructor who was the captain.
My team did a dive on a site with some current. We got blown off the ascent line and did a drift deco ascent. (Recreational dive, but a slow ascent with shallow stops.) We ended up a hundred yards or so from the anchored boat, and had a tedious surface swim back. I was later told that the captain had said, as he saw what was happening, "Well, I guess they aren't as good as they think they are!" And we weren't. Hearing that remark repeated to me made me very embarrassed, as I had not tried or intended to seem as though I thought I was God's gift to diving. Heaven knows, I have made and probably will continue to make plenty of mistakes!
With respect to trying to correct someone else, one approach I've found useful is to ask the person to critique ME. That opens the door in a very non-threatening way. Obviously, that doesn't work if the person in question wasn't diving with me.
If someone's attitude is sufficiently arrogant and bellicose, the likelihood they are going to listen to anything I have to say is pretty low, unless the dive itself makes them rethink what they are doing.
