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.
I'd say that it's impossible for teenagers to get 10+ bitcoins without help from their families. We shouldn't say too many teenagers. There's no way that a teenager can have 40 thousand dollars without inheriting it or getting it from wealthy family members. Most teenagers are spending whole days at school and dreaming about getting their driver's license and first car, or finally being able to move out to a small rented apartment.