These people comment only on difficult, controversial issues which are selected as issues where people perform worse than random.

Related, maybe they only comment when they have something original and unorthodox to say (selection bias). It's easy to echo conventional wisdom and be right most of the time; for a smart person it's more exciting to challenge conventional wisdom, even if this gives them a higher risk of being wrong. In other words, maybe they place a lower priority on karma points, and more on building their muscles for original thought.

Example 1: In my youth, I tried to only hold beliefs I could derive myself, rather than accepting what was told to me. As a result, I held many unorthodox beliefs, many of which turned out to be wrong. Statistically, I would have had a better track record if I had just accepted the conventional view.

Example 2: Robin Hanson. I think he is wrong a lot of the time, but he also thinks for himself a lot more than I do, and has advanced human thought way more than I have. He could easily hold more conventional views and increase his accuracy, but I'm sure he finds the risk and challenge appealing.