I tried to replace Twitter by Mastodon but, in the end, I just left Twitter and don’t use Mastodon at all. The main reason I think is because the « onboarding » is painful. I never succeeded to find interesting people to follow. I faced many ghost accounts from people posting once a month or stopped a few years ago.
If you don’t find people by yourself, no one is going to see your posts and so, you won’t be able to find new people to follow by posting.
I don’t like what Twitter became, but the base principle of the algorithm (before it became X with the paid subscriptions) was working great for me. I was constantly adding new people to the mix, and removing inactive ones every month.
If I struggled this much with Mastodon, I am not surprised many people create an account and leave a few days / weeks later.
I think it’s much more difficult to find people to follow. I personally struggle a lot, and will likely either gave up the micro-blogging system or try another platform. It was great on Twitter before Musk bought it, but since I left, I have yet to find an alternative.