Is shea oil an edible product?

It is. Good question.

So, I have to wonder, has the Western fad of shea butter taken away a valuable food resource, or is the financial trade off more advantageous?

Yes

Isn’t shea butter harvested in Africa for pennies or rice by tribeswomen?

They found a cash crop with high demand. I’m sure there is still plenty for the local economy.

I didn’t know until I went looking but it is, and is sometimes used as a substitute for cocoa butter. Apparently in Africa it’s traditionally used for cooking oil, among other things.