NYT article: good article about the ‘cumulative advantage’.
“The reason is that when people tend to like what other people like,
differences in popularity are subject to what is called “cumulative
advantage,� or the “rich get richer� effect. This means that if one
object happens to be slightly more popular than another at just the
right point, it will tend to become more popular still. As a result,
even tiny, random fluctuations can blow up, generating potentially
enormous long-run differences among even indistinguishable competitors
— a phenomenon that is similar in some ways to the famous “butterfly
effectâ€? from chaos theory.”