Prefrontal cortex matures in the mid twenties
The prefrontal cortex is one of the last brain regions to fully mature, reaching its structural peak in the mid twenties. Given its crucial role in mediating limbic friction, it’s not surprising that teens are somewhat more impulsive and driven by the short-term. The mechanism for forcefully reducing time-discounting is simply not fully mature. There seems to be an evolutionary advantage for decoupling frontal regions from genetic influences, though. What’s more, this might also explain why transformative breakthroughs in many fields are made by young scholars (e.g. Turing).