If we were to discount an investment, much like a US Treasury is sold at a discount to its face value, we would be accommodating the cost of our risks rather than discounting a good to meet our relative satisfaction. If we think about equilibrium and replace the idea of relative satisfaction with the value of risk, we can suppose that someone is willing to pay more for an investment with decreased risk, and less for an investment with increased risk.
If you were offered ‘$100 in the future’ or ‘$100 today’, you would prefer the money today. Why? Because at that specified moment in the future, the offer would be ‘$100’ or ‘$100 and all the money earned’ respectively. This assumes you were a reasonable person and invested the money to appreciate.