When you are planning to choose a web development company for your business website, just think of a toll road. Once the toll road is built, all that needs to be done is collect toll from all those that use it, and maybe some regular maintenance. as your business grows and your website maintenance cost increases. same is for a web development company.
Same is the case with a software products company. Once a product is developed, it can be scaled up significantly, So huge read operating leverage is possible in the milking phase, with little or no incremental cost. (We concede that the analogy with a toll road is not accurate, as there are implementation costs, custom modifications to fit clients, plus constant changes that make it dissimilar to a toll road. The analogy is just for illustration purposes too.