Fully agree with this analysis. Whenever I embark on learning a new topic, I'll typically buy 2-3 books on the subject, sometimes including an up-to-date textbook.

My goal usually isn't to become world-class in the subject, but to become competent or conversant in that subject. Reading even 2-3 well-chosen books can put you in the 80th percentile or higher, and capable of engaging with more knowledgeable people on the subject.

The amazing thing is that doing this regularly with new subjects has a strange compounding effect as your brain makes connections across disciplines. Sometimes this leads to insights that surprise narrow experts.