That's an exaggeration, even for frugal people. Retiring at 50 means ~30 years of working life finished and ~30 years of retirement remaining. At $50k per year * 30, that's $1.5m. Spread out over 60 years that's $25k per year before tax. I wouldn't say it's "relatively easy" to save for retirement, pay for healthcare, live somewhere safe, have children, etc. on that, even with investment returns over that time frame.