> Assuming the market uses real money, then on paper someone should be able to make a roughly 2% return by betting that the event won't occur. However, if this market isn't closing for a while (for example for an election at the end of the year), then no-one is incentivised to take the bet and correct the market, because they'll get a much better risk free return just by putting their money in a term deposit and collecting the interesting. And so the market remains un-corrected. Basically prediction markets have an accuracy upper bound determined by the current risk free return.

What if the deposited USD automatically earned interest at the current risk free return (think something like USDC on Aave in crypto land)?