You arguing completely besides the point. Yes the age when you are an "adult" is completely arbitrary and a subjective opinion that differs with every person.

You arguing completely besides the point. Yes the age when you are an "adult" is completely arbitrary and a subjective opinion that differs with every person. However for a society to function we have seen the need to come together and decide on some objective metric where you are allowed to perform certain actions that have the potential to cause yourself harm if misused. You giving your personal opinion that X years of age is not "adult" has no real bearing in this discussion. It would be more fruitful if you suggested some clear objective measure on how to validate if someone is legible for trading options because this seems to be an action were irresponsible acts can lead to huge demise. People can drive cars at 16, potentially leading to loss of own life, and others, if misused. Do you have an issue with that as well?