For your friends app, I had to go into the app store and then expand the description to view the key features, where it is mentioned that it uses AI similarly as Cal AI. Just based off the initial images of Eat compared to Cal AI, then it's much more clear what Cal AI does compared to yours (besides plastering AI everywhere).

Another thing I noticed is that I saw a random guy with a rather big following being sponsored by Cal AI. Maybe your friend was unsuccessful in getting his app out there? Although I agree that luck will always play a role, but when the public don't understand what it does and they believe it to be pure magic, then sprinkling that everywhere will get something like Cal AI flying.

I still think it is shit from a technical perspective in terms of the validity of amount of calories from a single image and nothing else. But it seems like that's not what people want, inherently because they are lazy. Actually counting calories is much harder long term. If regular people now think that this is magically replacing this process by just snapping a picture of their processed meal, then I can see why it's successful. Although quite depressing...

The worst thing you can do for a bad product is good advertising.

they did distribution well.

> So there's a lot of luck involved here

App Quality and Luck are not the only two factors that go into App Success.