An easy-ish way to understand why adolescents do dumb stuff is through brain development. The part of the brain that says GO develops way faster than the part that says STOP. Kids end up taking risks without thinking.
Activity in the ventral striatum to anticipated reward as a function of age, for each individual subject, showing enhanced activity between roughly 13 to 18 years. Teens are capable of making rational decisions, but in emotionally salient situations, risky behaviors will always win out because of developmental imbalance in brain.