I think it's very important to distinguish between two types of "experts". You do have the master bullshitters that are making grand or sensationalist claims who claim to know and to be sure before they are. But you also get a lot of scientists who are simply digging into their disciplines and slowly increasing our understand of something by continuing to collect data and to rule out wrong hypotheses. We should be careful not to group the two together as it would be throwing out the baby with the bathwater.
Additionally, a lot of scientific studies quickly get misconstrued by the media since the people writing the headlines have very little understand of what they are talking about. And while the actual paper might claim "our result show that there might be a correlation between substance X and condition Y and further investigation should be conducted to test for a causal link", the headline might be "Science proves X causes Y." Of course, as you've pointed out before, scientists are not always sincere in what they claim with their papers, especially with the soft sciences where experiments have smaller samples and are harder to repeat.
So not all experts are bad experts. But if someone calls themselves an expert, it's usually a red flag. If you watch interviews with actual scientists about their research, most of the time you'd see people talking about the unanswered questions, what they are trying to find and so on, not people claiming x and y with absolute certainty.
And if you are not talking just about experts doing science, but experts in the workplace, then yep, you often get the master bullshitters maintaining appearances of expert level knowledge without substance. Confident and charming incompetent people seem to do OK in the corporate world.