Earlier quoted context omitted.
> Bump it to two-thirds and retire in 10 years. Expand it by 100 and you would be already retired before you would were even born! I guess the point of the advice is to be realistic. > The only more important factor is "never borrow money", and in particular "never carry a balance on a credit card". Well, lots of people have started companies or saved themselves from starvation by maxing a credit card.
The idea that >20% savings rates are not "realistic" is a serious mindset problem. Almost anyone on Hacker News with a paying job (i.e. not an early-stage no-funding startup) should easily be able to save much more than that. Sure, saving two-thirds of your income might be out of reach, and even the 20% advice is better than most sites that often say 5-10%, but consider carefully whether you can increase it and retir…
Say I make $100k gross per year. That's a very nice salary for a new grad engineer -- the kind of person who might take this ten-year-retirement advice to heart. Roughly 1/3 of that income goes to taxes, so I'm actually taking home $66k per year. If I save 66% of that, I'm saving ~$44k per year. These numbers can shift a little depending on where you live, how you save, etc., but they're not going to change by a huge amount.
Multiply that $44k by 10 years, and you're not even at half a million dollars. That's not retirement money (unless perhaps your "retirement" is to continue to live off of $20k/year indefinitely and die young from eating too much ramen).
The other half of the equation is finding investments that return a reasonable yield without betting the farm on timeframes <= 10 years. In this market, that's nearly impossible. Your choices are stocks and bonds (which are fine, but are risky on anything less than a ten-year window), or investments that don't yield anything.