Why rendering takes so long?

I'm puzzled. Why does rendering take so long? I've noticed that the process seems to drag on for hours, sometimes even days. It seems inefficient and frustrating, especially when I'm eager to see the final product. Is it because of the complexity of the graphics or the sheer amount of data that needs to be processed? Or is it a limitation of the hardware or software we're using? Could there be ways to optimize the rendering process and make it faster? I'm genuinely curious about the reasons behind this delay and would appreciate any insights you could provide.