Objective: Face validity and the best available evidence strongly support the value of early intervention (EI) for psychotic disorders, and increasingly for other mental illnesses. Yet its value continues to be intensely criticised by some academics and doubted by many psychiatrists. This disconnect is examined through the lens of the ‘clinician’s illusion’. Conclusions: A number of sources fuel resistance to EI; however, the cumulative exposure to persistent and disabling illness that dominates the day-to-day experience of psychiatrists may be a key influence. This experience forms the basis of the clinician’s illusion, a hidden bias health professionals develop as a natural consequence of their clinical experiences, which shapes belief and perception of prognosis, and breeds therapeutic nihilism. This bias has been reinforced by grossly under-resourced systems of mental health care, undermining morale and adding a sense of learned helplessness to our mindset.