john titor
Captain
He was around for 100 years and the best he could do was lieutenant commander, irc? Also he was defeated by the cretin Neelix with a riddle about surviving without water or something like that so he clearly was a stupid vulcan. The only thing he seemingly was good at was martial arts so I'll give him that. He may not have been as career focused and so I don't think he was a complete loser, but for a Vulcan he may count as one.