Kevin O'Leary has one rule he pushes on everyone: take 15% of every dollar that comes in, whether a paycheck, a side hustle payment, or birthday cash from your grandmother, and put it directly in the market. In a video he posted to social media, he put a number on what that habit produces. Someone making $68,000 a year, the approximate average U.S. salary, and investing that 15% from age 25 to 65 will retire a millionaire. "Just let it compound," he said.
On paper, he's not wrong, and this seems like a smart retirement plan. Based on historical market returns, consistently investing 15% of a $68,000 salary over four decades could grow into a seven-figure retirement portfolio. The practical problem is that after rent, groceries, student loans, and utilities, the typical earner at $68,000 has roughly $716 a month left, not the $850 the rule requires.
Get instant access to hundreds of discounts
Over 50? Join AARP today— because if you’re not a member you could be missing out on huge perks like discounts on travel, dining, and even prescriptions.
Get 25% off membership — just $15 for your first year with auto-renewal — and a free gift if you join today.
How the 15% rule works
O'Leary's version of the rule doesn't carve out exceptions for different income sources. Paychecks, freelance work, cash gifts, and tax refunds. Fifteen percent of all of it goes into the market. He recommends putting it in a low-cost index fund and leaving it untouched. The idea is that consistent small contributions compounding over decades do more work than picking stocks or trying to time the market ever could.
Can investing 15% really make you a millionaire?
Fifteen percent of $68,000 is $10,200 a year, or $850 a month. Invested consistently for 40 years at the S&P 500's historical average return of roughly 10% annually, that monthly contribution grows to approximately $5.3 million. At a more conservative 7% return, the same discipline produces around $2.2 million. Either way, the millionaire threshold is cleared by a wide margin.
Can the average $68,000 earner actually save 15%?
At $68,000 gross, taxes and payroll deductions leave most earners roughly $3,600 a month to work with. Average rent nationally runs $1,750. Add groceries ($400), student loan payments averaging $434, and utilities around $300, and that's $2,884 in recurring monthly costs, leaving about $716 before any other discretionary spending, which falls $134 short of what O'Leary's rule requires. Individual budgets will vary, but the example illustrates why consistently saving 15% can be difficult for many households.
Resolve $10,000 or more of your debt
National Debt Relief could help you resolve your credit card debt with an affordable plan that works for you. Just tell them your situation, then find out your debt relief options.1 <p>Please note that all calls with the company may be recorded or monitored for quality assurance and training purposes. Clients who are able to stay with the program and get all their debt settled realize approximate savings of 45% before fees, or 20% including our fees, over 24 to 48 months. All claims are based on enrolled debts. Not all debts are eligible for enrollment. Not all clients complete our program for various reasons, including their ability to save sufficient funds. Estimates based on prior results, which will vary based on specific circumstances. We do not guarantee that your debts will be lowered by a specific amount or percentage or that you will be debt-free within a specific period of time. We do not assume consumer debt, make monthly payments to creditors or provide tax, bankruptcy, accounting or legal advice or credit repair services. Not available in all states. Please contact a tax professional to discuss tax consequences of settlement. Please consult with a bankruptcy attorney for more information on bankruptcy. Depending on your state, we may be available to recommend a local tax professional and/or bankruptcy attorney. Read and understand all program materials prior to enrollment, including potential adverse impact on credit rating. "Debt-Free" applies only to enrolled credit cards, personal loans, and medical bills. Not mortgages, car loans, or other debts. Results vary.</p>
Sign up for a free debt assessment here.
How Americans' savings rates compare
People aged 55 to 64 have a median retirement savings of $185,000, which shows what saving at the typical American rate actually produces over a career. The national personal savings rate sits around 4.4% of disposable income, meaning someone at $68,000 sets aside roughly $3,000 a year. That's less than a third of the $10,200 O'Leary's rule requires.
O'Leary's response to the shortfall
O'Leary's response isn't to soften the 15% requirement for people who come up short. His argument is that younger earners need to cut the discretionary spending they don't track carefully. Subscriptions, frequent dining out, purchases that feel small individually but add up to several hundred dollars a month. That's where he says the 15% has to come from.
Other experts agree on low-cost investing
Warren Buffett has made the same case for decades, recommending that most people put money into a low-cost S&P 500 index fund and hold it rather than try to beat the market. Suze Orman has argued that, given rising life expectancy, 70 is a more realistic retirement age than 65 for most Americans, and that workers often underestimate how long their savings will need to last.
Bottom line
O'Leary's rule is mathematically sound, and the gap between the national savings rate of 4.4% and his 15% target is largely a behavioral challenge. For most people at $68,000, the practical path to making the right money moves is to start with whatever percentage the budget allows, automate the contributions so the money doesn't pass through a checking account first, and increase the rate incrementally as income grows.
One factor that works in the average earner's favor is that the 2026 employee contribution limit for a 401(k) is $24,500. That's more than double what O'Leary's 15% rule requires at $68,000. Which means the full $10,200 annual investment fits inside a tax-deferred account, where pre-tax contributions reduce the year's taxable income and the savings compound alongside the principal over 40 years.
More from FinanceBuzz:
- Retire like the rich: 14 ways you could build wealth in your 50s.
- Find out if you could pay less for car insurance in just a few clicks.
- Make these 7 savvy moves when you have $1,000 in the bank.
- 14 moves seniors could benefit from but often forget about.
Add Us On Google