a big shot (in advertising)

Bill Bernbach had once taken great pains to teach me something relevant. He told me that there was danger in clients who came to an agency desperately in need of direction and guidance because, he said, "the same brilliance, the same guts you use to grab the bras ring and lead that client to a success will be perceived as arrogance and an irritation as soon as the client is successful."

-"A Big Life (in advertising)" by Mary Wells Lawrence