The real threat is not that fast-food worked gets job at Jimmy Johns, decides sandwich business is great, decides to open competitor.

The threat is potential competitor decides he want to open sandwich shop. Already has the capital in place, doesn't have the experience. Decided to get a job at Jimmy Johns to learn how they operate. I have no idea why people dismiss this like it's crazy. If you were already set on opening a hamburger shop/chain, you wouldn't stand a couple of months at minimum wage at McDonalds to see how a successful McDonalds franchise operates?