I'm allergic to business books, but I think a flywheel is a better metaphor by a mile. A flywheel is a tangible object that everyone has interacted with at some point. They're fun and satisfying to spin up to high speed. They are associated with engines and electricity. In contrast, inertia is an abstract concept. It's popularly associated with dead weight. It makes you think of heavy rocks and ships that are too large to maneuver quickly. It's not at all fun.