Recent stats show that there are over 4 million apps available between the App Store (iOS) and Google store (Android). Unfortunately, most of the users take many of them for granted. They pick and choose without acknowledging what it takes to build an app. If you are familiar with this subject even the slightest bit, you know that it is a lot of hard work to come up with a unique idea for an app.
Usually, one would have to target an issue/requirement people have and develop a solution that will add value by resolving this issue. Then, once the idea is born, you have to build, test, and promote the app or find someone to do it.