Teenagers can be challenging to be around. Hormones, attitude and all the drama can make it a hard part of life. Most of that is due to brain development. While 18 is the age of legal adulthood, the brain isn't fully developed until about age 25. The limbic system, which is all about immediate gratification, pleasure, and impulse develops sooner than the pre-frontal cortex which is where logic and long-term planning comes in. The striatum is another part of the brain that is very active in adolescence. It's where rewards are processed, and teens love rewards because the striatum is highly engaged when they feel rewarded. It's also where risk-taking happens. Teens will risk much more than adults if they think a reward is involved.
From an evolutionary angle, this risk and reward are what works in the animal kingdom. Going away from the safe family, and into the unknown is necessary for animals, and in humans, the same urges are hardwired into the brain's development, but the choices available for teens are not just maturity and new places. Drug use, risky behavior, and other negatives are often in the environment of teens, and it's hard for them to resist. So, be patient, teens will eventually catch up, they won't be like this forever. In the meantime try to encourage risks like taking a class they wouldn't usually think of, or joining a new activity.