How much money does it take to make one Bitcoin?

I'm curious about the economics behind Bitcoin mining. Could you elaborate on the costs involved in creating a single Bitcoin? Is it a fixed sum, or does it vary based on factors like mining difficulty, equipment costs, and electricity expenses? Given the volatile nature of the cryptocurrency market, how do miners manage to stay profitable? And what kind of investment is required to set up a mining operation that can potentially generate a significant amount of Bitcoins? I'm eager to understand the financial realities behind this digital asset.