It's interesting you use that analogy because my dad was an author of chess books. Yes, many were a niche within a niche and only sold a few thousands copies.

My observations about business books match your intuition—the more popular business books tend to be popular for reasons beyond their educational content. They usually include great storytelling, are meticulously crafted and edited, and are about societally interesting subject matter beyond the pure educational aspects.

But that really makes a difference in your experience as a reader. I'm not saying popular means good. I am saying that on average with all things considered the popular business books tend to be better experiences to read than the unpopular ones. Of course there are exceptions.