Log utility is a fairly extreme way of discounting huge rewards. A less extreme way is to consider that there is only so much money or wealth in the world, on t

Log utility is a fairly extreme way of discounting huge rewards. A less extreme way is to consider that there is only so much money or wealth in the world, on the order of $100T. Huge payouts would require printing more money, reducing the relative value of all money. So a linear utility function for a finite world looks like x / (1 + x/$100T).