the reason you're are still more or less a child is for a few reasons.
#1 your brain isnt even fully developed yet. there's a reason you are quick to take a bunch of dumb a.. risk that you shouldnt when you're that age. you're brain isnt developed enough to say ehhhhh maybe i shouldnt try that. thats not smart. maybe i should do this instead.
^^just in case you thought i made that up. lets go to a reliable source. you can also just google " what age is a human brain fully developed?"
^^thats #1.
ask yourself why is 21 the age for legal drinking? now there are all sorts of reasons they agreed on that age. but they surely didnt say 18. and you know the beer and other alcohol companies would've loved for it to be 18 so they could get 3 more years worth of profits. But ask yourself, how many times have you seen a 21 year old drink him/herself into the ground? and think thats cute and cool?
now what if you couldnt get a drink until you were 25. do you know how many less alcoholics we would probably have? how many less DUI's you would probably see, traffic accidents, etc.
What if the legal driving age was 25. how many less accidents would you see?
all of the negative things about being that young are due to the above comments about the mind not being fully developed until around 25 yrs old. it doesnt mean no 25+ yr olds do stupid ish. they do. we all have. it doesnt mean you dont have bad drivers at age 40. we do. it means there would be a lot LESS of the stupid emotional moments. and you would have people that would not have created a bad addictive habit for themselves at such an early age why their mind was developing. so odds are less people would be addicted to things due to this.
why do you think the armed forces like 18 years old as an age? you're not in your prime strength/athleticism yet. that happens later in life. But what you do have is under developed minds without complete minds of their own that you can still some what mold. basically sheep you can heard and tell them what to do and they will do it. brainwashing someone is much easier to do with an 18 yr old than it is when you're 25 or 27 (your athletic/strength prime).
Why do you think most music artist skew younger? Its because the labels want to be able to use you up without you complaining about it and taking a stand. they can mess with your contracts and you wont be old enough to understand how and why this is happening to you. even if you're smart. they can over work you and you not say stop because you are a kid in the relationship. they know this. there's a reason they dont like to sign older artist often. they will have to Deal with a fully grown man or woman, they dont want that. even if you have talent.