how can common or small-minded people understand the great ambitions of a visionary person?

to live in a state of false security or lose vigilance due to comfortable living, remaining unaware of impending disaster

To lose vigilance through comfortable living and remain unaware of impending disasters; to live in a fool's paradise.

How can a person of low position understand the lofty ambitions of a great person?

To congratulate someone on the completion of a building project or moving into a new house.

Eurasian chaffinch or common chaffinch (Fringilla coelebs)