Remember, "civilians" advance about half as fast as Starfleet/military officers. So, 8 advancements reflect about 16 years experience in the profession.
Someone mentioned something about Command. Honestly, the only characters that I would require have Command 1 would be the ship's master, first officer and chief engineer. Only a commodore in the merchant marine should have Command 2.
The merchant marine organization is much "flatter" than Starfleet's, with less formality between the ranks, and even officers and enlists. They're all professionals, and treat each other with more equality than would a Starfleet crew (where the rank structure is more stratified).
Davy Jones
"Frightened? My dear, you are looking at a man who has laughed in the face of death, sneered at doom, and chuckled at catastrophe! I was petrified."
-- The Wizard of Oz