Guys want a 500 horsepower car. I'd rather have one horsepower - in a horse. That's macho. You go to pick up your date and you show up on a horse.
Psychologically I should say that a person becomes an adult at the point when he produces more than he consumes or earns more than he spends. This may be a the age of eighteen, twenty-five, or thirty-five. Some people remain unproductive and dependent children forever and therefore intellectually and emotionally immature.