If you are a hard no-afterlife-is-possible, you will never actually experience it. If you are right, death = end of all experience.
If you are open to there being an afterlife, you will be better prepared for one if it happens. If there is no afterlife, you will never know you were wrong.
Given the above, it is reasonable to presume that our instincts and inklings that morality matters should be heeded. It is reasonable to look for signs of an afterlife. It is reasonable to prepare for an afterlife.