The virtual-coin model
A social casino gives you a free coin balance that refills on a timer, plus daily bonuses, missions and friend gifts. When the balance runs out you can wait, complete a task, or buy a coin pack. Coins cannot be cashed out, exchanged or transferred for money — that is precisely what keeps these apps outside real-money gambling regulation in most jurisdictions.
Revenue is concentrated: a small minority of players buy most of the coin packs. The game design is tuned around that, with escalating pack offers, limited-time discounts and loss-triggered promotions.