As many of the other replies allude to, there's living and there's living well.
When I retire I want to live well and in good health. Depending on what age I retire it will likely take over $1M.
Retirement investing books are interesting. They talk about a 4% draw down on your investments during retirement in order to not run out of money too early and figuring out your expected life expectancy based on actuarial tables and your parents' health.
Sure you can retire at 55 years old without a mega-buck, but the risks that you will either end up broke in a medicaid nursing home or die early due to lack of ability to afford medical treatment goes up dramatically.
I plan to retire at 55, but only if I can get closer to 5M in equity investments. That way I can afford to live well while retired, traveling regularly and not concerned about food stamps.