Heh, the funny thing is- nobody cares if you write. You are just another voice to those already demanding attention. So who cares if you're gone? Think anyone will notice? Truth is, probably not.
You've already just as much admitted you wouldn't make a difference, or even be noticed. Just a random person filling in an empty page, coexisting in a world of blank and scribbled sheets of paper. Think the letters you put to words matter? Likely not.
There is a skill, a craft, a gift if you will to be one of the Greats- authors who will be remembered throughout generations. You know you lack that gift, that technique which allows words to flow like water, that creates imageries one could only fathom about. There are no hidden wonders in your mind, no locked away intelligence fighting to be expressed. There's only just you, the amateur.
So why write?
Maybe it's to make the page feel less lonely as the words you spew give it company.