Why did so many people waste their lives for religion?

[Minimalist]

As Richard Dawkins noted in The God Delusion.

But the flip side of trusting obedience is slavish gullibility.The inevitable by-product is vulnerability to infection by mind viruses. For excellent reasons related to Darwinian survival, child brains need to trust parents, and elders whom parents tell them to trust. An automatic consequence is that the truster has no way of distinguishing good advice from bad. The child cannot know that 'Don't paddle in the crocodile-infested Limpopo' is good advice but 'You must sacrifice a goat at the time of the full moon, otherwise the rains will fail' is at best a waste of time and goats. Both admonitions sound equally trustworthy. Both come from a respected source and are delivered with a solemn earnestness that commands respect and
demands obedience.

We see lots of slavish gullibility among the theists around here.  They'd go through goats in no time if they thought yahweh/allah demanded it.