Future earnings should only be discounted solely with a risk-free rate if the future earnings themselves are certain, i.e. risk-free. But they aren’t, so you ha

Future earnings should only be discounted solely with a risk-free rate if the future earnings themselves are certain, i.e. risk-free. But they aren’t, so you have to account for that with a steeper discount. Your $100bn earnings are shrouded in uncertainty, so as an investor you demand compensation for taking that risk, hoping that the earnings will materialize.