I have developed personal obsessions with subjects that required serious study to learn about, and often found instances in which the material was soOoOOoo dry, tedious and dull that I could barely stay awake through a single paragraph and had to reread the same paragraph over and over sometimes, before I could grasp what the hell the author was saying. And I knew I wasn't stupid.
All I can tell you is that having encountered almost identical resistance when I first started seriously working out physically, the brain reacts very much like a muscle. When you begin to tax it's limitations, it's very hard to get anywhere. The only solution is to keep working it. The more you force yourself to ingest raw information without the sugar coating of fictional adjectives, the better your brain will get at digesting that kind of material, and eventually, it not only won't seem so excruciatingly, agonizingly boring, it will start to become easy and interesting because the new data is entering the brain smoothly and being interpreted and understood, rather than choked down and filed away, like an unappetizing, but "good for you" food.
It might help to use dry scholarly works on a subject you're actually interested in to practice on. It took me nearly four months to plow my way through the first volume of Joseph Campell's 'The Masks of God.' It took four weeks to finish volume four. Now it's as easy to read as a Stephen King novel.