⚠ Habits Follow the Better DrugModerate threat

Physician familiarity keeps prescribers reaching for the drug they know, but it is among the softer advantages in medicine, and it yields when a clearly better or cheaper alternative arrives. Doctors are trained to follow evidence, and in a field where efficacy is measured in controlled trials and real-world outcomes, a rival drug that demonstrably works better will win prescriptions despite any incumbent's familiarity. Habit slows switching; it does not prevent it when the clinical case is strong enough.

The danger is that the incretin market is both lucrative enough to attract enormous competitive marketing and fast-moving enough that prescriber habits are still forming. Rivals invest heavily to build their own familiarity, cheaper drugs would give payers reason to steer doctors toward them, and the next generation of incretins could reset the whole prescribing landscape. Familiarity built over a few years of leadership is real but shallow compared with the decades-deep habits that protect older franchises.

Lilly's familiarity advantage is genuine and reinforces its lead, and the company works continuously to deepen it. But an owner should recognize that prescriber loyalty in a rapidly evolving, fiercely contested drug class is a supporting advantage rather than a durable moat, that it bends to superior efficacy and to payer pressure for cheaper options, and that it cannot be relied upon to hold Lilly's franchise if a rival — and Novo is trying¹ — delivers a meaningfully better or more affordable drug.