Earlier quoted context omitted.
>but as a business owner in a different field I'm left wondering why anyone would even bother. Because they don't have a choice.
They have a choice. An economic profit is defined as making enough profit (and intangible benefit) to not want to do something else. For a small business owner it's "am I better off selling it off and getting a regular job?" For a larger chain, it's "is there a more profitable line of business?"
There is a lot of ego in a decision like that. Easy economically, very very hard emotionally.