The ROI is the return on investment . It's the same as the expected value, or EV.
It's a GIVEN in this question, so we'll just have to assume that we accept the number and it's based on some kind of fact of reality. Perhaps years of results. BTW, this would mean - on average - the Hero is earning $30k, on a $10k event. This is obviously WAY BEYOND THE PALE for a real life situation. But let's just assume it's true: you're a poker player who earns 300% on his money every time he sits down to play. Perhaps you're playing with retarded people, or you're cheating children. Let's run with it...
Mason Malmuth has already shown how to do similar math. Normally this question is formulated along the lines of:
What is the EV for Strategy1 vs Strategy2?
Notice in this example, the OP never mentioned the number of entrants. It's impossible to answer the standard question without knowing the number of entrants.
Since we already know the EV. What don't we know? We don't know what he's doing to be this Mr. Super Beast with a +300% ROI! He's almost certainly cheating, or something like that. Probably then you should dump the aces, because you'll have way better than 4:1 chances in the future, and since you can see through the cards or something, you should wait.
The fact we can calculate the odds of winning hands against these particular ranges [4:1 and 3:2 respectively], doesn't give us enough information to calculate the answer to the question.
Again, Malmuth has shown how to answer this if we assume we don't know, a priori, the EV of the Hero. That is, if you assume everyone has the same skill level, you can do this calculation. I'll leave that for another day! However, in this case we are given the Hero is some sort of savant. We know that's not because of his normal, that is average skill, so we can't answer strategy questions. We don't know what kind of game he is playing!
So the answer is: IT DEPENDS ON WHATEVER STRATEGY IS GENERATING THIS RETURN ON INVESTMENT. You cannot calculate it in the standard way, vis-a-vi Malmuth, which assumes equal skill.