This assumes littering is a conscious action. Plastic enters the oceans primarily through negligence; unconscious actions of people that do not think about (or are unaware of) the consequence of the action. Once the consequences of one’s actions are raised to the conscious level, people can make rational cost-benefit analyses of their actions and would probably think twice about throwing their rubbish into the environment. And what better thing can one do to raise the topic into the public awareness than by executing a very visible project like The Ocean Cleanup?
Right now, the oceanic plastic problem is quite an abstract problem. Since the patches aren’t solid masses of plastic they’re difficult to photograph, and, in any case, they are very far away. By lifting the plastic out of the ocean and showing the world mountains of trash coming into port, we remove the abstractness of the problem and bring it much closer to home.
Cleaning plastic from the ocean, as well as all the R&D required to make it happen, also helps to increase the available knowledge of the problem, as our numerous scientific publications have shown. This, in turn, allows us to develop better technologies and policies to also address the prevention-side of the equation.
The moral hazard argument can also be countered by the Broken Window Theory, which says that that visible signs of social disobedience (graffiti, litter, etc.) promotes more of such behavior. People are, for example, more likely to litter when the park they walk in is already littered. By making the ocean clean again, we avoid the idea that the oceans are already full of plastic and that one extra piece of plastic won’t make much of a difference. Saying that the oceans can’t be cleaned up and the only thing we can do is to try to not make it worse is a very depressing message. If the oceans are truly polluted forever, why bother trying to do something about it?
Following the logic of the moral hazard in reverse, it looks like the best way to stop plastic pollution will be to stop collecting litter from the streets and remove any waste infrastructure because these things all give people an incentive to create more waste in the first place. Obviously, that is not true. The data shows countries with the least amount of waste infrastructure have the highest rates of plastic leakage.
As always, it is important to make a balanced assessment between a hypothetical risk in the future, versus a certain impact today.