Bitcoins have been over a couple of hundred dollars for more than 5 years now. Kids can only get so many by mining. Don't imagine too many teenagers have 10+ bitcoins without family help in getting them.
Bitcoin is maturing, and so are its holders.
Alts are probably a different story
This thread won't be too useful if it's not added to the survey in it, this will only be a speculation for many people without any
evidence. You should add a survey about the age of the user, it could be a clue of how many young people in Bitcoin