As the other poster pointed out, I was heavily inspired by TweetDeck which I've been using for 6+ years.
And yes, I agree that's a nice suggestion, user/content discovery is definitely a big area in which this can be improved.
Edit: I realized I forgot to answer the last two questions.
Plans for the project: I'm a realist so I don't think that it will be able to compete with Twitter. However I would like this project to become the go-to option for people who are already inclined to prefer decentralized/self-hosted solutions, and simply be better than the other software in that space.
No, I don't plan to monetize. Mastodon is open-source, licensed under AGLPv3. However I do have a Patreon through which interested people could support me while I work on it.