Comparing tuition to the growth of the S&P 500, or any fund or stock for that matter, is like comparing a first class dining experience to a computer, the two have nothing in common.
Why would you expect education costs to move with the value of public businesses? How does that make any sense? A businesses worth has actually gone up (acquired assets, generating more revenue, etc.), has the value of a college education gone up 400% from 2011 to 2022? Because that is what you seem to be suggesting. Are new grads from BU on average making 400x what they were in 2011? Even going from $51k to $79K that's about a 47% increase, is BU college education 47% better today than it was in 2011? Probably not.
A 4 year BS is $320,000 without Room and Board. That's what my mortgage was 22 years ago. I have 30 years to pay that off, and I can live in it while doing so.
(Now, multiply by the number of children you have, in my case, 2.)
$51,574 invested into the S&P 500 in 2011 would be worth more than $225,000 today.
BU enrollment was 32,727 in 2011, and is currently 33,678. I'm surprised it hasn't gone up considerably more.