How do you earn money in sandbox?

Could you please explain to me how does one earn money in the sandbox environment? I'm quite intrigued by the concept and would love to know more about it. Could you elaborate on the various methods or strategies that individuals can adopt to generate income in such a setting? Is it primarily through transactions or is there more to it? Also, could you share any insights on the potential risks or challenges associated with earning money in the sandbox? I'm eager to understand the intricacies of this process. Thank you!