Of course it's not a scam. What you see is what you get, and nothing is hidden.
What it is is a money-making tool that leverages customers' desire to grow their money, by creating the possibility that something may go up in value, leading people to buy while the developer gets a cut. Anyone who looks at it will quickly see that supply and inventory exist entirely in secret, and entirely at the developer's whim, which makes it a very, very stupid investment.