No it is most definitely not a ponzi scheme, Darkcoin has real value to the end users as an anonymous currency. If you want to invest in the infrastructure of Darkcoin and help provide that service you get a reward. It is not proof of stake. Masternodes are actually a lot of work and represent a risk.  You can make money different ways, either by investing in a young project with potential so your investment appreciates over time, or provide a service to the network, put your capital at risk and receive a reward. Or create an economy around it sell dark to people in your country charge a commission, start accepting dark in your existing business or create a new one.