Might be life changing but not everyone wants or needs that level of discipline in their lives or 4 years of service after school.
A graduate of a Military Academy serves an appointment of a minimum of 8 years, at least 5 years in active duty assignments, then they can choose 3 years as inactive reserve (5 and dive). If the career chosen requires additional training the appointment may be longer.
So yes, that's a big commitment for a 17-18 year old kid to make.