Blaming this on cost doesn’t really make sense. Sex and minor delinquency are extremely cheap forms of entertainment (as long as you successfully avoid pregnancy).

Both of those generally involve you being in the same physical place as some other kids, which requires some combination of transportation and real estate, both of which cost more than they used to.

Meanwhile if they know you can't afford to do anything other than get into trouble somewhere then your parents aren't inclined to give you a ride, so instead you sit at home on your phone.