Pet Projects: Level-up Or....?

Do developers need pet projects in 2024? We will discuss: where to get knowledge from - from courses or trying to make your own application; why you need to make your own services and applications; if you make a pet project, it means you are not loaded enough at work? whether it is possible to make money on pet projects; what to do when a pet project ceases to be a hobby, and whether it is a hobby at all; open source as a way of self-expression.