One analogy is to liken tiktok (and shortform content) as exploring the shallows. Walking around, close to the shoreline, you explore pieces of flotsam that the sea washes your way. You might spend a lifetime on this shore, walking up and down, but most would argue that you've actually never gone anywhere.
On the other hand, reading a book is like getting on a boat. You've made certain preparations for acquiring the vessel and set course through unknown territory. A journey away from the shore and away from what's immediately at hand, which can also turn out to be a journey towards self-discovery.