Expertise grows deeper and deeper as you work with an ever more specific subset of situations and individuals whose needs match the solution you provide.
And while this is indeed the desired outcome in the pursuit of becoming any sort of expert practitioner, it also highlights the need for a strong separation between work life and personal life.
Applying that same all consuming appetite to keep learning to a varied and interesting personal life keeps your work grounded in a broader context, and lets you come back to it fresh each day.