How people actually grow on social media today

Lately I’ve been thinking about how unpredictable social media growth has become. One day a post gets ignored, the next one suddenly gains traction for no obvious reason. It makes me wonder whether it’s still possible to grow organically without any external help. Do you rely purely on content quality, or do you think using different promotion tools is just part of the game now? I’m curious how others approach this, especially when starting from scratch.