It is not 70% of kids, and this number is not hard to look up. It has been trending around 30% for enrollment into 4-year institutions. Of those, ~60% complete the degree within 6 years.

I agree that most students who got to college don't make good use of the time or investment, but it is still a minority of people who even attempt college.

https://nces.ed.gov/programs/digest/d18/tables/dt18_302.60.a... https://nces.ed.gov/FastFacts/display.asp?id=40