Patanjali Yoga Sutra 2.9

Abhinivesha flows by its own juice; it is established even in the learned.

स्वरसवाही विदुषोऽपि तथारूढोऽभिनिवेशः ॥

sva-rasa-vahi viduso 'pi tatharudho 'bhinivesah ||

Abhinivesha flows by its own juice; it is established even in the learned.

This is a deep, existential anxiety—the fear of death, the fear of an illness returning, or the fear of being a "nobody" if you lose your job or role. Being highly intelligent does not make you immune to it. It is a natural human instinct, not cowardice.