I am totally amazed at people that are experts in one field and pretend to be experts in a completely different field.
It took them years to get a PhD in one field and they read one book in a different field and by magic now they are experts in something totally unrelated. They are so self absorbed that they think their opinion matters in everything else. When I was in college I knew quite a few college professors that would go on and on about something they knew nothing about. But they felt that their single PhD made them an authority on everything.
Not to mention most PhD’s are focused so specifically to a particular subset of the overall field they are in, sometimes they don’t even fully understand their own overall field of study. I see it all the time in computer science PhD’s. Some of them can recite theory of database structure, but couldn’t tell you the first thing about IP addresses. Or vice versa. And I’ve seen plenty of proof this happens in other fields of study as well.