Re: THC, the active ingredient
The amount of methanol produced by the distillation of grains, potatoes or sugars is in the ppm range and poses no danger at all.
It was bootleggers adding wood alcohol (methanol) that caused the issue. Methanol is an optic nerve poison (hence being "blind drunk").
Mixing sugar, yeast and water and drinking it wont poison you or make you blind.
Nor will it make you blind after fermentation and distillation.