B&S- Option to delay

Sir let’s say the NPV of a project if invested in right away is X amount, and if invested in 2 years later is X+20(value of an option to delay), then when we are discussing the reason for an increase in NPV if we wait for 2years before taking up the project, then do we just talk about the 5 variables that go in a B&S formula or that we can also talk about other factors outside this formula? Like reduction in the number of competitors in the industry? growing income of people, or burgeoning demand?