I think most exchanges do not ask for their age. You can also use your father/mother ID
DO NOT MAKE THIS MISTAKE. Take it from me, I used to work at CEX.
Its fine for an underage to have bitcoin, at least here. Its property/value; kids can have money all day without breaking any laws.
But using a platform is an entirely different beast. The platforms have a liability to protect children from certain content, and prevent them from engaging in activities that might be illegal (say like, trading illegal securities for example). They establish a TOS to protect themselves in this; you usually agree to the terms in order to use the Service. If If you lie about you age, they are under no obligation, legally, to return your funds to you. So if you get locked for a verification check, and you cant provide proper ID, you may not have recourse for obtaining your funds.
which brings me to another thing, lying to an exchange about your age/identity. exchanges follow strict aml/kyc law; they must know who you are in order to accept and hold more than X money from a person. when you lie, you make their job harder, and bring them out of compliance if its found they have lax identification policy. so they have little incentive to help you; you lied, they have your money, and you cant do too much to change any of that.
Ive seen it happen.
Dont fuck around with this, you will be disappointed eventually.
Very good point mate. If the trading platform "caught" you cheating their system by lying about your age and all the pertinent information then you are fuck up specially when you are about to withdraw all your funds and can't because they needed verification for KYC/AML complaint. Its no different from gamble sites as well. I remember there was one member here who's account get lock and further investigations show that he is really underage but showing proof of his parents or something like that. He/She wasn't able to withdraw their money because from the very beginning they have intended to cheat the system.