Gadaffi claimed that Libya was ruled by the people. He was a captain when he staged the coup and he accepted a ceremony to become a Colonel.

That and I've read Colonel is the highest rank in the Libyan Armed Forces

A followup question for Gaddafi, how much of him keeping the title was influenced by him wanting to imitate the trappings of Nasser and did he legitimately believe in what Nasser was selling at the time?