https://bigthink.com...shrooms-evolved (this one even talks about how it could give them a bad ride, making it less likely they'll eat it again)
It think you may have misunderstood my post. All I meant was psilocybin is a defense mechanism. At the end stages of life, the hypothesis is that the fruit puts more energy into preparing for spore drop than the continued manufacturing of psilocybin. I'm not saying all of it goes away, but it stands to reason there is a reduction in its production therefore a drop in potency.
Thanks, those links eventually got me around to a story on The Atlantic that I'd read back when it came out in 2017 outlining the hypothesis.
And the articles have some compelling points, but psilocin/psilocybin as a defense mechanism is still just a hypothesis.
Some counter-points that I also find compelling include the fact that there is very little to no psilocybin/psilocin in vegetative mycelium (or we'd all be growing the hell out of it and not bothering to fruit our cultures). If the drug is used as a defense against getting eaten then it seems to me that it would be much more effective toward that goal if it were produced as soon as possible after the spores sprout (i.e., in the mycelium).
Also, the insects that eat mushrooms would be helping disperse the spores (by sticking to their bodies) and eating a mushroom does not harm the underlying mycelium, so mounting such a metabolically-expensive defense for a temporary and replaceable fruitbody seems like a waste of energy considering that the vast majority of successful mushroom species do not contain any of the molecules under discussion.
The effect on insects could very well be incidental and not the primary purpose of producing psilocin/psilocybin. Same goes for their effect on us, but these are just hypotheses as well.