Devices that run the Android operating system (phones, tablets, etc.) account for over 72% of the world marketshare. The Google Play Store raked in $38.6 Billion (with a "B") in 2020 all based on the development of Android applications.
There are fortunes to be made in Android Apps. There are over 12,000 searches per month for Android Application Development. Advertisers are paying $14.95 per click on their ads.