When you tell anyone about your personal projects, you'll lose ~90% of the motivation to finish the project.

Oh no I've been discovered! This is not a safe place any more...

Hey, stop stealing our ADHD memes! There's clearly not a very very noticeable overlap between our communities.

Wasn't there a study that found if you tell people you're working on something, you get the same brain reward chemicals as if you actually did it and told everyone? So if you tell people before you're done, you might just go "meh, I'm good, the rest sounds hard". Or something like that.