+1Getting a particular sound, tone, etc., is much different than thinking it will make them a better player. I've personally never met anyone that thought they'd be a better player as a result of something more expensive or "nicer". In some instances it's true though. If you have an old ass guitar with a broken truss rod, and the strings sit a half inch off the fretboard, a new guitar will most certainly make you a better player.
A new instrument will make you a better player IF there is something about your current instrument that is holding you back.