My observation is that whatever story people believe will happen after their death will deeply influence their current life in this reality, so I disagree that it is “just wasted time“. For most, it’s not simply a mind exercise but defines their values and existence.
It’s arrogance and ignorance of the “West“ to assume everyone wants to “live a long life“. You very distinctively have other priorities if you believe in reincarnation and karma. Belief in rebirth strengthens dynasties and collectivism in very real ways, the belief in no afterlife or one that is not influenced by your current behavior strengthens individualism.