listener = listens to music... can be about anybody
instrumentalist = plays an instrument. must be a listener too
musicians = MAKES MUSIC. you can be a listener, or an instrumentalist, or both, even neither! just as long as you create music, create something out of nothing or another form and turn it into music
if you're a listener, you are the best candidate on being an instrumentalist, since ear is the best friend of any one playing an instrument. More so on being a musician.
IMO, the best ingredient in musicianship is not dexterity (or chops on your instrument) or musical knowhow (music theory etc), but life experience. natutunan ko to kay victor wooten. Sa chops (instrument) you can just get a lesson or two and practice yourself and you'll develop an acceptable level in no time. Sa music theory, there are just 12 notes/pitches, you can stop from there already, or dig deeper. But those two are just tools - what is important is if you're telling something of if you have a story to say.
so, being a listener may or may not qualify you as a musician. But if you create music out of your experiences (musical or otherwise), then you are a musician in every sense of the word.