Many people think that expression is now a cliché, especially motivational speakers and I side with that and rightly so. For I believe knowledge lies in waste if it isn't activated. Someone reads or knows something but doesn't put it to practice, the value of what they know can't be quantified or measured. So, it's a waste. Those who knew (knowledge) of Bitcoin when it was created but didn't make a bold move by buying it then can't be selling it now. I believe that explains the how thing about knowledge being "potential" power and not "real" power. It's not an automatic thing.