A community has certain expectations when you join it and is likely to take punitive action if you violate those expectations.

That consequence should factor into your reasoning of "what is in my best interest?", in the same way why you don't usually want to perform petty crimes IRL.

As a hint, how is 5 different from 2? Is 2 not rational or not in your best interest?

I read 2 as "I will perform the most rational actions among the subset of those that lead to a net positive for the community", whereas 5 takes away everything from 'among' onwards.