The stock market is definitely not a Ponzi scheme. As its name says it's just a market where people buy and sell very tiny pieces of real companies, based on some predictions, in order to make a profit. It might look like a Ponzi scheme because of the greedy nature of humans. The real problem with the stock market (especially in the US) is that people are indirectly enforced to invest in inflation-protected assets, like stocks and commodities, as a consequence of the aggressive monetary policies, which in the end trigger a vicious circle where money printing becomes a one-way highway, but the stock market itself is not the evil here. I've written an article about that, you can check it to get more insights.