I am useless

Am i a human, or a beast who knows only to feed.
Why am i a parasite, why do i suck entities dry?
Where am i human? he wouldnt hurt a fly
Why am i here? what have i done !
But im helpless, these things i must do
Why even my parents, why dont i let them be
I pester them always, never let them at peace
A bike, a car, a cell; greed that drains their banks
I hurt my loved ones, not me; my greed
But i feel guilty, i repent for my misdeeds
These are not crocodile tears, i must make you believe
But from a fly to the sky, its me who makes them cry
But to live i must hurt,
For otherwise, i must die
I am a symbol of pain, of death, of hell
I am a murderer, for without doing so, i cannot survive
Im a sinner, for ive sinned for a long time
But without sins, im somebody redundant
Im somebody, wait a nobody
I mourn for the people i hurt,
But without doing sins, i must die
Without sins, i have no hope to survive.

Where am i, what is my need?