Imagine for a moment a white plastic spoon in the middle of your living room floor, now imagine for every square meter of your home there is one plastic spoon. Now, alone, not so many spoons, one per meter, no big deal. Now imagine that for every spoon you see there is a dust pile made up of that same plastic, just under the carpet or in a corner.
So your house, with it’s spoons and its plastic dust is constantly accepting new spoons and plastic dust at a rate of 1 spoon a day and one pile of dust per day. You can’t stop that , it keeps happening because the people outside of the home only see the one spoon in the middle of the floor or the one little pile of dust in the corner, but they don’t see the one int he landing or the one under your bed, etc
It’s dispersed, it accrues in the animals and on the coasts, there is a VAST dispersed web of plastic and it hangs down into the largest area of our world that spreads over 70% of the surface.
But if it helps, imagine constantly finding dirty plastic spoons in your living room; and you can’t stop them from appearing.