Companies usually have a business model. They produce something that a target market will pay for.

Steem's only source of money flow is the investors themselves, and the invested money is distributed between content creators (and other rewrad earners) cashing out, the founders and early birds cashing out, and yet the investors expect to get at least as much money out of it as they invested (otherwise, what's the point of investing?).

So more money is flowing out of the system than into the system, unless they balance this by constantly increasing the number of new investors.

Unless of course, investors are not in it for the returns. They accept that their investment will be distributed and they will actually lose money. But in this case, steem is either an over-complicated tipping platform (assuming investors are generous like that), or a glorified advertising platform (assuming investors are not just tipping out of generosity).