The Free and Open Source Software movement is an extremely important cause because not only does it affect software and the computer industry, but society as a whole. It is a movement for the freedom to tinker, reverse engineer, innovate, and, the most crucial of all, to freely share knowledge.
Slowly but surely, computers and software are invading every aspect of our lives. With the rise of AI and IoT, we are effectively surrounded by computers 24/7/365, and it will only get worse. Not to mention the data which they collect on us and who is able to see (exploit) it.
It is absolutely vital that we have control over our devices. That means having the freedom to access the code and the freedom to modify it. The less control we have, the larger the knowledge divide grows, and that is not a good recipe for a healthy society.