What is success? It is a toy balloon among children armed with pins.

Gene Fowler
Gene Fowler (1890-1960) American journalist, author, and dramatist. [b. Eugene Devlan]
(Attributed)

This is attributed in multiple sources to Fowler's Skyline: A Reporter's Reminiscence of the 1920s (1961), but searches of two copies do not find this text.

In her biography The Whole Truth and Nothing But (1963), Hollywood columnist Hedda Hopper wrote:

One of the men I loved most above all others was Gene Fowler. He once wrote me a letter from London. “What is success?" he asked. “I shall tell you out of the wisdom of my years. It is a toy balloon among children armed with sharp pins."

The line is also shows up in Art Cohn, The Nine Lives of Michael Todd, ch. 19 "I Love You" (1958).