[Scheherazade]

That belief would make people sad, it'll never catch on.

If it makes people sad, there's no reason that it should catch on.

According to Jeremy Bentham, that which produces the greatest good for the greatest number is all that matters.

So if believing we are... demigods produces more units of pleasure than believing the former, there's no reason why we shouldn't choose to do so.

...unless one believes in some eternal reward in the afterlife for enduring more pain in this life for believing "the truth" or something

[One Degree]

Since my post was to see what others thought and not to represent an opinion I hold, I will refrain from addressing most of your points.
The one point you make that is of significance is what about people who do not pass on their genes?
Have they found a way to overcome their hard wiring or have their genes reached a dead end and no longer wish to be preserved? In other words, are genetics somehow based upon what is best for something other than the individual?