I would agree they should be equal EV or at least close, 50% to 60% is pretty nuts. People like to quit after finishing free spin bonuses as well. That might be the logic, but I'm not sure how sound it is. I did advocate for the instant win prize to be raised closer to the expected return of the free spins. The players that take the free spins are more likely enjoying the game and will probably continue playing. No, I never heard an explanation but I would speculate that the many of people who are taking the instant win are more likely to cash out because they have a 'big' win.