If you’re creating something – whether that’s sales copy, a new video game, art, a book, whatever – it is helpful to know if it’s for you or for other people.
If it’s for other people, hopefully you’re taking the time to make sure that these people want what you’re creating. That you understand their worldview and how to meet them where they are.
If it’s for yourself, hopefully you’re taking the time to make sure that it’s what you really want, and that you’re okay with it just being for yourself.
After it’s made, you might find that something you built for others also ends up being for yourself, or that something you made for yourself ends up becoming something bigger for other people.
But often failure stems from confusing the two. A project that is for others but you treat like a personal hobby doesn’t reach as many people. A project for yourself that you try to share may find itself limited by the size of the niche.
Neither is right or wrong, you just need to be clear about who it’s for.