If you built it, they wont come. Without marketing, the odds of your customers discovering the app (amongst a sea of garbage) are insanely low. I tried a Tennis app in 2009 and even back then it was competing with hundreds of other apps, now its mist likely 10’s of thousands. Heart breaking.
Sometimes if you build it, they will come.
I launched a music app in 2012 (student project), and over its lifetime (6 years), I had 95k downloads and 7 million sessions on the app.
Some apps have very low viral aspects like biz apps or Utils, also some standalone single player games. They will be at the bottom of a search result of 100s when first released. Quite demoralizing
Word of mouth marketing can be strong. For example I have purchased many apps because of a recommendation IRL, mostly music-focused (musicians love to talk about their kit). The point is to make something truly excellent, and if possible, conspicuous.
