At first I was confused because of my mental rule of thumb that in a Bernoulli choice, p=0.5 is highest variance. But that is when the payoff is 1, of course!

At first I was confused because of my mental rule of thumb that in a Bernoulli choice, p=0.5 is highest variance. But that is when the payoff is 1, of course! When it's not, we're really looking at payoff² * p * (1-p) and indeed the second situation has much higher variance.