if you say should or ought to, you are declaring a judgement (the thing is either beneficial or not, and non-beneficial in some way becomes a should NOT judgement). Your internal rules (what we generally call morality) is what typically underlies such decisions.
Where does morality come from? It is largely learned when young, but it originates from the minds of man. We all respond to events in some way, and we dislike those things that cause negative emotional feelings and thus tend to find them to be things that should not be done except to avoid even worse outcomes.
You show us your true nature as a human being by your choices of actions. We will all judge your value to us other humans in terms that we have decided are best for ourselves.
We have to have an operational code to avoid chaos and anarchy. You do not have to accept that code, but we will reject you from our society if you find our codes to be unacceptable. You want your own rules, off you go into your own world because we cannot have that in ours.
Even wild animals develop such behavioral codes. It is beneficial to the continued existence of the life form. Each for himself is just a quick road to no one left.