There are close to 1800 calories in a 5 pound bag of potatoes vs 700 calories in a 10 oz steak. Pretty sure your dollar amounts there are vastly different from what is found at the grocery store.
Ancient human beings didn't have grocery stores, though. We're talking about what ancient human beings would have thought about the price of hunting vs. the price of gathering, not what modern humans find at a grocery store. Killing one wooly mammoth would have generated enough calories to feed an entire tribe for months.
Can you try to explain your point at some greater length, perhaps?
My point is that when viewed through the lens of economics, meat was a vastly less expensive way for ancient human beings to obtain calories than plants were.
The situation for ancient human beings would be equivalent to a situation today (for modern human beings) in which 3000 calories of fruits and vegetables would cost $500, whereas 3000 calories of steak would cost $10.