"Private nonprofit four-year colleges charge, on average, $27,293 per year in tuition and fees" [1]
And that's just the private schools. The public schools are considerably cheaper: ~8k USD for in-state students and ~12k for external students. 50k USD is the full prize for the top private schools like Stanford or the Ivy League. Imagine how expensive some schools would have to be for the average to come out at 50k USD.
Would be interesting to see a study focused on student debt and decision making around founding a startup or diving into entrepreneurship. On the one hand, those who graduate without a lot of loans would be financially enabled to dive into e'ship. On the other hand, loans might actually influence and be a driving factor for recent graduates who couldn't land jobs to create their own businesses.
but that is micro-business formation where there debt load is not a penalty due to the low costs of setting up a micro-business, vastly different from a start-up where debt load is a penalty factor
Let's use historical data instead of back of the envelope guesswork.
Over the last 40 years (1970-2010) the average S&P 500 return has been 11.61%, while inflation has been 4.4%. Past performance not necessarily but usually predicting future performance, but, with those rates...
Over the next 40 years $100k would grow to $8.1 MM in future bucks, or $1.45 MM in 2011 dollars.
The UK was about £3300, now under roughly £7000.