How Can Humans Abandon the After Life Myth

I've been reading summaries of after-life concepts in the period of 10,000 or so years BCE. The authors I'm reading studied the archaeological results of what appear to have been royal burials. Various parts of the world treated the dead differently and the same areas changed royal burials over time. Some royals (I'm using the term "royals" here even though it is not always known who the dead were or why they were buried in splendor) were buried with slaves who were killed to serve them in their afterlife. 

A lot of the study is in Egypt where the dry climate preserved things. In some places, royals were buried with their bodies adorned with jewels and make up. In other places the bodies were not adored but expensive and rare objects like jewels and gold plus food were near the bodies. Sometimes many other bodies, sometimes young people, were lying next to the royal. Sometimes there were dozens of bodies in the ceremony. Implied is that those killed at the death of the royal served some purpose in death.

In all cases, the narrative is this: There was life after death. That is, there was for royals. Was it available to poor schmucks? 

In Christianity, people are not killed to serve the dead in afterlife. But the people who died earlier are there in the same capacity, to make the dead happy forever. Could one say the concepts are both similar? Happiness after death is the sales pitch in either case.

Those who wrote the Bible were smart guys. The message to poor schmucks was, "Do what the wealthy want you to do and you, too, can enjoy a bountiful afterlife." Even the poor were charged a 10% tithe.

Perhaps since the beginning of humans there has been a fear of death which various schemers jumped on as an opportunity for power and money. Even though Christianity is declining, my guess the fear of death will remain and eventually someone new will exploit it.