What is the golden rule of money?

In the realm of cryptocurrency and finance, the golden rule of money often begs the question: what is the fundamental principle that guides sound financial decisions? Is it diversification of investments to mitigate risk? Is it the discipline of saving and investing regularly? Or perhaps, is it the wisdom of avoiding speculative bubbles and overleveraging? The questioner seeks clarity on the one golden thread that ties together successful money management strategies, across all financial markets, including the rapidly evolving world of cryptocurrencies. The answer, no doubt, lies in a blend of these principles, but the question begs for a concise articulation of the essence of sound money management.