Why can't we be just... done? Why is software development a never ending treadmill? App does what it's supposed to, the developer earns something (or doesn't),

Why can't we be just... done? Why is software development a never ending treadmill? App does what it's supposed to, the developer earns something (or doesn't), and they can I dunno, abandon it if it wasn't successful enough and the API breaks, without any guilt? Do something else with their life?