Bhagavan Vishnu makes a very profound observation that spiritual aspirants can ill afford to ignore: O Sage Durvasa! Austerity and knowledge are both conducive to spiritual welfare for persons endowed with humility. But in the case of devotees lacking in modesty and filled with excessive pride, those very things lead to contrary results (Srimad Bhagavata 9.4.70).
Overweening sense of self-importance and domineering manner makes one vulnerable to even the smallest acts of other people, however inconsequential they may be. Craving for constant public acknowledgement and acclaim to spiritual eminence makes many devotees vulnerable.
Notwithstanding all austerity and penance, a devotee can still be a prisoner of his own narrow ego. His mind is still a playing field for the three gunas and subject to violent mood swings.
The poison of pride vitiates all the noble virtues in a person and renders them worthless. Even scholars and sages are not exempt from the stigma of self-conceit. That is why in the very opening line of his Vishnu-shatpadi Adi Shankaracharya, an embodiment of humility, prays for the removal of pride: .O Vishnu! Remove pride (avinayamapanaya vishno).
The best ethical and spiritual qualities are of no avail without the support of the golden virtue of humility. And humility is an expression of expanded consciousness.