This is also how I see it. Most of the power is already in your brain, although of course you get better by practice. But for many people the power is somehow "locked". Something you find in the book, or doing some exercise you find in the book, may help unlock the power.

Evo-psych hypothesis: Everyone has the power, but there is a mechanism detecting that "your status is too low to do this", which turns off the power, to avoid punishment by higher-status members of the tribe who want to preserve the social hierarchy. But the mechanism is an adaptation to the ancient environment, and is often miscalibrated today. Something in the book may help turn off the low-status feeling. (Perhaps even the fact that someone with high status, such as the author of the book, encourages you to behave high-status, can be perceived by the mechanism as an evidence of your status rising. It could be an equivalent of getting a powerful friend.)