That is correct. But returns have to be considered in context.
First, you need to consider the holding period. We hold those trades on average 5-7 days. So making 5% in less than a week is not too bad.
Second, you need to look at the risk. We rarely lose more than 7-10% on those trades, so the risk is relatively low. And the winners can be significant, especially if the overall market volatility spikes.
And the most important thing - as I mentioned, it could be a cheap black swan protection. So you basically have portfolio protection AND get paid for it. I'm not familiar with another strategy that can hedge your portfolio not only for free, but actually produce gains.