> Why would someone contribute to an AI project without getting paid?
Because there exist people who are in deep love with mathematics, but weren't able to get a research position (or cannot afford to take a temporary position at some university for which they would even have to relocate).
So, your question is more like: why would someone play a video game without getting paid?
Because there exist people who are in deep love with mathematics, but weren't able to get a research position (or cannot afford to take a temporary position at some university for which they would even have to relocate).
So, your question is more like: why would someone play a video game without getting paid?