Why does subway exist.

They Charge 5-8 dollars for a crumby sandwich, with crumby ingredients. You can get better sandwiches from damn near any deli or supermarket for 2-3 dollars cheaper. It doesn't make any sence. Also, when around town with friends we've thought there pizza around the corner, only to find out it was a subway. How does this even happen? It's not like subway has pizza style sandwiches, this smell to food relationship, is also wildly concerning to me. They promote weight loss, you can probably loose  weight eating their sandwiches because they are so fucking terrible you cant finish one, or you just expel it through your mouth upon completion.