Free and Open Source Software

Since we're on lemmy, I'll use this as an example. If someone were making a GNOME (GTK4 + libadwaita) Lemmy frontend, and I were to start working on my own Lemmy frontend for GNOME, thereby competing with this already existing project for users, is that wrong? To make things more interesting, what if I wanted write my Lemmy client in Rust since I didn't like the original being written in Python? To make things even more interesting, what if that project is slow in development due to the developer not having a lot of time? My gut instinct is that it is immoral. I feel like I would be taking away a project that the author had sunk some amount of time in, hoping to impact others in a positive way. I understand there is no guarantee that my project does better than theirs, but I should still be conscientious of the possibility, right? Let me know your thoughts FOSS community.