Unfortunately that’s not really true and they find they wasted a lot of time and money and have no prospects and mounting debt.
After person spends 12 years in the public schooling system being educated and after tax payers have invested hundreds of thousands into that person the result should produce a functional adult capable of filling more than 50% if not closer to 70% of middle class jobs in a given nation.
Instead for the last 30+ years we have pushed more and more jobs out of reach for a person with a standard public education largely do to decreasing standards in that public education combined with the self reinforcing feedback loop up university funding.
This is the true cause of the erosion of the middle class that is perceived to be happening. 20-30 years ago most jobs on the market did not have a degree requirement, and there were many middle class jobs that people with out degree's could fill. As we pushed the jobs more and more to have a degree (any degree not even a degree in the field just any random degree will do), with it means many people are starting their adult life in massive debt, where before the it would have been a home, or something like that.
If we want to fix the nation, the solution is not free College for everyone (like many young people and social democrats want to propose) the solution is to make a standard K-12 Education applicable again for most middle class jobs
Interesting thing is, a bachelor's degree in Europe is basically that advanced K-12 you're suggesting. The main difference is that it's way cheaper, and occasionally faster (2-3 year programmes are not rare, certain countries have a degree between high school and research universities).