If you click through to the original article[1] linked by the blog post, they explain that
> Warren Buffett became a player in the investment game at the wee age of 11, eventually using cash he earned from his paper route to buy some farmland in his home state. As a high school sophomore, he also reaped the rewards of a booming pinball machine business.
1. http://www.marketwatch.com/story/from-6000-to-67-billion-war...
A high school sophomore would be 15-16, so he would have already made the $67k (adjusted) before he got into the pinball business.
Few people start working as early as 13-14, but if we extrapolate the $175 a month (which would be almost $2500 in today's dollars), and you had no expenses you could save $150,000 by the time you were 20, today.
Must surprising here is how well paid that paper route was. Average salary was $200 a month in 1944. Today the average salary is $2500 a month, but you can't earn as much from such a simple job today.