This really is true. I find that most people take what I say seriously, even when I've wandered out of my depth and am basically bullshitting. Being white and male helps, speaking standard American English helps more, and as I get older, I get even more credibility. If I wore a suit, I probably would get more credibility still. Just recently I was in a shoe store as a customer, and another customer ignored all the sales people (who were Asian women) and started asking me questions about the product--apparently because I was the only old white guy in the room.
This is not true of all white men, but it is true of a lot of us. If I state the one fact I know about a subject, I apparently radiate such conviction and authority that people assume that this is only a small sample of my vast knowledge on that subject. I’m basically an ice cube that constantly gets mistaken for being an iceberg.
For a close relative of mine,(RIP), this turned out to be something like a tragic flaw. He was very good at convincing other people (and himself) that he knew what he was doing, even when he didn’t. Consequently, he was often put in positions of authority and power before he had developed the necessary skills, and ended up disappointing every one, especially himself. I think this was more than he could take, which was one reason he left this earth far too early. I don’t expect any marginalized person to feel sorry for him, but I hope you will forgive me if I do.