Gold is a common food decoration and considered edible, but of no nutritional value.

Most plants are slow acting poisons, they don't want to be eaten. Humans have a tolerance for some level of some poisons... Many nuts have trace levels of cyanide, but people eat them anyway.... Beans if not soaked can make people very sick, etc ...

The core problem is lots of people eat things that aren't ideal - especially when starving.

Lots of people have gluten sensitivity, they get a inflamed gut when they eat it, but they eat it anyway.. so it's a poison, but it doesn't kill them quickly, and they will argue gluten is a food...

There are very few perfect foods with no downsides: eggs get pretty close, but even then some people have allergies