Drinking alcohol is also a very unsafe way of getting your caloric intake! That's what makes being a human so fun: There's never a correct answer.
Mycotoxins are only produced by fungi, so you might be wondering: Why are you fermenting mushrooms? Well, the answer might be because mead has used a huge number of flavorings and adjuncts over the years (learn more about that in The Wildcrafting Brewer), but the real reason is that yeast (which is also in the fungi kingdom!) can help deal with toxins from molds and other things that were a major problem in the past
