The actions we do have a price, to study, have a family and be able to be successful, all of that has a price and although we question the result is achieved, sometimes the moral does not enter into our decisions but if we need to obtain the goal, we accomplish whatever. The decision of Thanos is morally bad view, but if he wanted to change the story for the good "that is frowned upon by me" but he got what he wanted, he did it in spite of everything and that is so weird but he did it.