At the very minimum, the fruits of your labour are useful to your boss/customer. That is already a single positive impact in someone's life right there.
Most likely, your boss/customer then used your developments in their primary business, which, no doubt, affects even more people in a positive way.
I believe being in technology, we have the capability to positively affect many orders of magnitude more people, than in most other industries. So cheer up! ;)
People waste money all the time. Maybe the OP's boss paid him three years salary to do something the boss thought was important, but really just wasted time. And nobody knew it wasted time, because it was hard to measure.
A personal example: At a small marketing agency, my boss insisted we needed to offer social media marketing, since "everyone's on facebook now a days." Because we were posting on behalf of clients, we didn't have the expertise to write about the goings on of their business, and often had no contacts in the client organization. We were forced to write pretty generic stuff ("happy valentine's day everybody!" or "check out this news article"). Worse, we had clients who shouldn't be on social media in the first place: plumbers, dentists, and the like. I have never seen anyone like their plumber on facebook. So naturally, these pages were ghost towns.
Yet despite having zero likes and zero traffic, clients insisted on paying someone for social media (They too had read that "everyone's on facebook") and my boss never refused a paying customer.
Want to know how it feels getting paid day in and day out to make crap content that nobody will read? Feels bad.