Who says they lived a happy life? Who says they wouldn't have lived a happy life otherwise?
We don't know that. All we know is that the drug made them become obsessed with something irrational.
Would you take something like that? Would you want something like that to become widespread? Do you want a society that is far more religious and devoted to their religion?
Why do you condemn people that find something different to help them with that than you?
There is a difference in having a spiritual experience and merely following a ritual for the sake of the ritual.
It anything, more widespread LSD usage would make people less religious by your definition.