Not hard, actually. Suppose you are 25 years old, today. You run your own little software consultancy business, and average $200,000 a year in revenue (before

Not hard, actually. Suppose you are 25 years old, today. You run your own little software consultancy business, and average $200,000 a year in revenue (before inflation), in perpetuity. You max your IRA every year ($5500 tax advantaged). You also have a Solo 401K, in which for Tax Year 2017 you can contribute up to $18,000 a year as an employee and a total (including employer -- your business -- contributions) of $54,000 tax-advantaged dollars. We'll ignore "catch up contributions" and the fact these limits increase over time, and make this a round $60,000/year. Let's assume that, after expenses, averages a 4.75% return over 40 years. Conservative, but let's roll with it. Based on the calculator the SSA provides, your monthly SS benefit is ~$6500 at age 65. After 40 years, you have ~$6.75M in your tax advantaged accounts. With a conservative withdrawal rate to keep your lifestyle the same, you can have ~$220K in retirement income a year (in today's money before taxes taken into account) w/ SS. However, the problem with that is you'd never draw it down. Even if you adjusted it for inflation, you'd die long before depleting your savings.