A long time ago I saw a presentation that started with the premise that 60% of everybody is crap at their job. Doctors, lawyers, airline pilots, and even scientists. Of course that's just a number pulled out of the air, but the idea was that even if a person studies something for a long time and even if they pass some standardised tests, they can still be bad at their job.
I've met completely incompetent programmers who had advanced degrees and tons of experience (not 60% of the field, mind you, but enough to realise it does happen). The field of science is not immune to this. I remember my brother telling me a frightening story of going to a first year science lecture and the professor saying that correlation implies causation. He put up his hand and said, "You mean does not imply causation, don't you?" The professor said that, no, if it's correlated it means that one caused the other. How can you get a PhD in science and also manage to land a job at a university (reasonably well respected at that) and be so confused at such a basic level? It happens, though.
Sometimes even very smart and capable people have huge blind spots in the way that they think. Again, I've worked with a number of programmers who were extremely talented and intelligent but were unable to program anything that didn't turn into a massive ball of spaghetti. They could barely keep it working (due to their intelligence and talent), and nobody else even had a chance. This is sucking at your job, even though you have the mental hardware and skills to do a good job. It happens -- everywhere. In all walks of life. I remember the case of the airline pilot who got sick of waiting for air traffic control to give him the OK to take off. He decided to go anyway and killed hundreds of people including himself. Apparently he was a very experienced and skilled pilot.
What you are seeing is not a pattern that involves scientists. What you are seeing is a pattern that involves people who are self-deluded and over confident. I mean we could put "Actor" in for "Scientist" in your points and it would read just as well. Yes, the field of science is not immune to this kind of problem.
I think the main thing is that if an actor says something stupid we think, "Oh they are just an actor". If a scientist says something stupid, we tend to think that maybe they should be doing better. A scientist's job is to think critically, build models and test them objectively against the data. When a scientist seems incapable of doing this basic task, maybe we need to wonder if they are actually able to do their job well -- because lot's of people are crap at their jobs. Even scientists.