Stable coins are not dollars or euros. They are something else. Something way riskier than holding plain dollars. That's why you are getting rewarded with that fat interest rate. It is not free money by any means. You are taking a risk and I must say, for the amount of risk you are taking 5% is nothing because stable coins can go "poof" any time and you better ROI your initial investment before they do otherwise you'll lose everything there.