This is largely discounting the third scenario, advertiser or viewer is actively hostile. Top comment above goes into the first of those two, but ads are frequently a gateway to all manner of scams, cons, and fraud. A cost largely born by those far less clever and more vulnerable than those participating in this discussion. On the other side, you’ve got things like click fraud. While not huge relative to ad volume, the costs and externalities are also huge compared to the money changing hands in these transactions normally and probably tips the scale significantly.
This is largely discounting the third scenario, advertiser or viewer is actively hostile. Top comment above goes into the first of those two, but ads are frequently a gateway to all manner of scams, cons, and fraud. A cost largely born by those far less clever and more vulnerable than those participating in this discussion. On the other side, you’ve got things like click fraud. While not huge relative to ad volume, the costs and externalities are also huge compared to the money changing hands in these transactions normally and probably tips the scale significantly.