Your example is wrong.

All situations should be evaluated and re-evaluated at every instance, at every moment in time to account for new information and not only once at the beginning thinking it'll be the same forever.

Fishing as an individual its fine until too many people start doing it, then it becomes even bad for the individual. It becomes harder to fish, the fish get smaller, the prices drop, etc. Some of those things might be even good for society but not for the individual. At that point you've got to re evaluate your position, and even change your occupation. This is what happens all the time. Individual choices lead the way, society only acts after enough individuals have been affected, not before.