"Fairness and justice are human concepts. They do not exist in nature or in any magic of my kenning. I call it a redeeming quality of your species to try to rise above its environment, especially when considering all your limitations." - Baron, red dragon of the Dire Straits
I still don't know where I found that one, but it's pretty good. It's also true. In a pure material world, good and evil is entirely relative.
It's good for me, so I want it. It's bad for you, so I don't care. But, you can't run a society on that. You need shared values. You need trust, and for that you need reasons to trust. The more advanced tech, the larger the base needed, the more people need to trust. And, for the vast majority of people, they need that framework to hold together, and for that, they need a God.
Even amongst intelectuals, there aren't that many who can create, and sustain, morals from reason. Ans, those who can, cannot form a society. Attempts at doing so have resulted in the Woke faith, nothing based on reality.
To boil it down? You might be able to create reasonable morals, but you're not the average.