Suffering is not the same as having a reward function. If the outcome is a reward, people would opt in for suffering to get rewards. Some even cheat their ways to rewards. People do hustle porn, virtue signaling, other fake sufferings. Some push to the extremes like running triathlons. But at some point, reality will wake us up. Our personal struggle is always there. It never ends. We'd be forced to make intelligent choices. Or we'd die wasting our time on useless endeavors.