A couple of weeks ago, I built a little app to help me keep track of all the Eevee Pokémon cards and which I own. It's nothing crazy, and only took a few hours to build. I was proud of my little app and showed it off to my friends.
Then, as I was getting deeper into Dex—app I use to track the rest of my collection—I realized I could do exactly the same thing, more easily, and more beautifully. In Dex, I made a smart folder to only show cards that are Eevee and its evolutions. Easy. And it even shows which I own, which variants I own, and has filters, sorting, etc. Features I would've liked to build into my app, but didn't.
I could be stubborn and stick to my inferior app, but that would be shortsighted. Building your own thing has costs too—time, hosting, maintenance, etc. So I'm deciding to abandon it. Despite what some might think, it was not a total waste. I learned from making that little app. And that is priceless. Probably.