Something like this happened the first night the crew moved into the Deathworld Mansion. I was upstairs, and started to walk down, only to find one of the actors chatting with the crew. He was an actor by trade, and was explaining to the crew on their first day that movies were really all about acting, and everything else was secondary. For this reason, he went on to explain, it should really be him directing the entire project since was the one with experience in the only thing that really mattered. True story, he then went on to have a few drinks and explain how L Ron Hubbard had a plan for their lives, and had uncovered the secrets of the alien volcano lord Zenu, for the shared benefit of all human kind.
You have to work with people and look for intelligent ones, but these days, it shouldn't come as too much of a surprise when you run into a crazy entitled person with minimal wit.
The bad thing was that that speech ended up doing a lot of damage. Some of the crew were actually convinced, because the guy talked loud and confidently, and I've seen that happen a lot. People don't understand how Dunning/Krueger works, so about half the population just follows whoever is the loudest and most boastful.
I also once had the wife of an actor physically push me aside and impatiently show me how to point the camera at things. She had never used a camera before. Later on when the footage turned out really well, she acted shocked, you could see the mental gears grinding as she tried to parse the idea that anyone besides her and her husband had been competent. I laughed, fired the husband, and replaced him with someone who could act. But I guess the joke is on me, because I saw later that she had directed an Instagram photo of her lunch, and both her husband and one of her friends had liked it.