That is a pretty big assertion to make: that on average, most of the tax collection over the entire US is paid by non-college graduates.
Income of mid-career is 111,000 (college) vs 43,000 (HS) [2]
Lifetime increase in earnings is estimated 800,000, paying taxes the whole time.
So I think the commenter calling this a one time tax deduction is closer to reality than a "regressive tax". Probably less regressive than the 401Ks many college grads have vs HS.
[1] https://money.com/wage-gap-college-high-school-grads/ [2] https://www.cbsnews.com/news/how-many-of-us-are-college-grad...
Taxes are paid on income, not on people.