More than extra income
A side project is often judged by revenue, users or whether it can become a full-time business. Those outcomes matter, but they are not the whole return. A good project can also build judgment, technical ability, distribution, confidence and relationships.
Options compound
The useful question is not only Will this succeed? It is also What will I be able to do after working on it? A project that teaches you how to identify a real problem, make a product and reach an audience can remain valuable even when its original form ends.
Product thinking as personal practice
Product thinking is a way of paying attention: noticing friction, choosing whose problem matters, reducing an idea to something testable and learning from reality. Practised consistently, it changes more than the products you make. It changes how you direct your own development.
This is starter content. Replace the general examples with lessons from your own side projects.
These notes reflect my thinking at the time of publication. Ideas may change as projects, evidence and experience change.