The purpose of ethics
While we like to think about ourselves as being good people or people wanting to do good, we, the Western Civilisation, have abandoned the concept of a universal morality defining god two hundred years ago, together with the universal morality itself. Since then, all our considerations about ethics have been revolving around the sphere of social consensus rather than objective reality, and we have seen multiple attempts to redefine what is "right".
However, the existing state of affairs begs the question: if morality and ethics are a product of societal expectations towards an individual, should you care for them?
The short answer is "yes", which is not surprising at all. However, what is surprising, at least to me, is the fact that ethics serves a deep, protective purpose to the society - less fortunate people can build alliances against luckier, stronger and rogue individuals. In other words, you can build your power with others to power over subjectively overprivileged people and restore subjective balance a bit faster than without ethics. More, thanks to strong ethical principles, you can stop at the equilibrium point, preventing others from forming alliances against you.
Ethics is a society stabiliser if used appropriately.