Those numbers are a bit ridiculous, but part of it is definitely mis-education.
I have a finance degree (so I considered myself pretty well versed), and until I found MMM, I was under the impression that I'd probably need $4-5M in order to retire at normal retirement age. Looking back is tough because I can't forget what I know now, but the math made sense at the time. It also mirrored what our financial advisor (Edward Jones) had said, too.
The Shockingly Simple Math article was a real wake up call for me. The number got cut significantly (to about $800k-1M) almost overnight. Oh, and it also cut off about 25 years of work, too.
I'd guess most people think they need significantly more money than they do. By the time their 60's roll around, they probably actually crunch the numbers are realize that they'll be fine in retirement and tens of millions of dollars weren't necessary at all.