Does the potential winnings include your stake in the calculation as it is not total returns just winnings? That might be another reason for the difference? Hard to believe Hills would make an error as obvious as this in something that is computer driven.
It is a bit odd, as it is just a piece of software, no "opinion" goes into the Cashout figure.
Maybe it is because Ripple is a supersized ice-cream in the Marky bracket?
V good result, guess there must be a programming error somewhere, seems more likely than them deliberately overpaying someone? Guess they could have a strategy of generosity to encourage people to use it, though as others have said, there seems little need in such a strategy when people will just flap and cash in regardless of the EV.