The afterlife meme is so powerful because it does confer several psychological benefits to the believer. It can be very comforting to believe in being reunited with lost loved ones. It can also be very motivating to believe in eternal rewards and punishments. Many religious adherents can't conceive of morality existing without it.
The people we interact with will be forever changed, for better or worse, by our interactions with them. We can spread happiness and joy to those around us, or make them angry or miserable. We can have a small impact or change someone's entire life, and that change will affect how they interact with every person after that.
With the butterfly effect] you can never tell when one of those changes might be the tipping point in something momentous. Being rude to that waiter could be someday lead to genocide. Best to put out good vibes just in case.
While our consciousness may not live on, its impact will reverberate through the ages in the collective minds of all humanity, spreading the joy or pain we caused when we lived to ever person who will ever live after. If you live a good live and spread joy to others, your afterlife will be joyous. If you live a life causing others pain, your afterlife will be misery. Not just the in way that others remember you, but in how they have been impacted by your actions.
These real and undeniable phenomena are the source for our belief in an afterlife. Heaven and hell are perfect allegories for the way our positivity or negativity live on. For the believer, adopting this point of view has the advantage of grounding unprovable claims about the afterlife in reality, eliminating the inevitable baggage of doubt that any unprovable claim carries with it. For non-believers it can help add meaning to life knowing that our actions will have untold impacts on future generations. It also allows both to understand each other so much better.
Instead of arguing over whether or not an afterlife exists, the conversation should be about whether or not this undeniable reality of how our actions live on is the source of afterlife beliefs and traditions.