But how did Bitcoin start to have value before the Silk Road? It didn’t start with investors coming into the system to bid, and holders to sell, and as new investors came in, the market and the value of the coin didn’t become larger?
You said that Bitcoin stopped being "a natural occurring Ponzi scheme" once it was recognized as a currency in the dark markets. Why did they recognize bitcoin if it never hadn't been used as a currency or a medium of exchange before? The thing is that it has constantly been used as a medium of exchange since its very first exchange, which was a situation where a guy bought two pizzas (real goods) for bitcoin. According to the definition you provided, that was the turning point when bitcoin stopped being a Ponzi scheme and started its development as a currency. But before this happened, no one was trading bitcoin for real goods or other currencies, everyone was just mining and casually sending useless transactions. No one was expecting to become rich from hodling bitcoin or selling it to others, so there was nothing there that indicated any signs of a scheme.