The players were playing for the pot but that money was provided by the facilitators. Players were guaranteed a minimum pay for incentivization. That aspect isn’t like no-limit poker. The limitations were established by the budgetary constraints. If you tried, you could lose all “your investment” in the game in one hand barring the payment for experiment participation which is based on your performance in however many rounds you lasted. That’s what my interpretation of the text is.

Variety writer