Twitter is my favorite app, but it's because I have spent five plus years curating my feed.
There is a fundamental problem with the way they onboard new users and this is why so many people don't stick around.
The onboarding process asks you to select interests and then recommends people to follow based on those interests.
However, they often recommend celebrities and 'popular' accounts.
These people are often terrible at Twitter, so new users see a bunch of boring, self-promotional content in their feed and don't come back.