A question regarding the origin of 'dangerous food'.

The Japanese eat pufferfish. (Or used to eat pufferfish, or it is a delicacy, whatever.). We know that pufferfish is potentially deadly if not properly prepared.

My question is: How many people died before some chef figured out how to prepare pufferfish?

There are other ‘dangerous foods’ out there. (Some plants that need to be boiled for quite some time before consumption). How many people have died while these rogue chefs tried to figure out how to prepare said food items? And why the heck did they bother?

Cassava is a good example; it’s extremely toxic unless it’s prepared (pounding, soaking and heating I believe).

The reasons will vary, but I suspect that necessity is one of the primary motives; If you’re stuck in a place with limited food resources, all sorts of things start to look edible.