FACT: There is plenty of human food cheaper than pet food proving that people eating pet food because they...

Where did you hear this myth?
It's a new one to me

Where do you live?

It's your burden of proof to prove your own claim.

https://www.nytimes.com/1975/12/16/archives/meanwhile-humans-eat-pet-food.html

All I find about this is an article from 1975, so perhaps your issue is that it is no longer true that people buy pet food instead of human food.

Do note, pet food is usually the scraps that are excluded from human meat products. In practice, this lesser meat is significantly cheaper than the human quality meat but the costs are hiked up by the time the consumer buys the cans from the pet store.

Cat food has got to be more expensive than cheap cuts of meat, but damned if I'm going to make up my own cat food so I just pay. Now a can of dog food may be cheaper than a pound of hamburger, as dog food is cheaper than cat food, but isn't dog food full of grains and other fillers?

So while dog food may be cheaper than a pound of burger, it can't be cheaper than a quarter pound of burger, pureed with oatmeal and potato peels and table scraps.

spam might be cheaper than cat food.

Here is the real FACT:
https://greekreporter.com/2021/07/10/hunger-crises-caused-more-deaths-coronavirus-2020/

That’s probably mostly true although I’m sure there were incidents of people doing it.

I remember an article that talked about how when dogs in the wild kill prey they first go for the innards of the animal. Alpo made a dog food made from the innards that dogs liked and was nutritious for them but people wouldn’t buy because it was unappetizing to them.