Andre Nader, a former Meta employee, used the 'mega backdoor Roth' strategy to save and invest in tax-advantaged accounts.Nader built a seven-figure portfolio by following fundamentals of saving and investing in index funds.As a high-earner, Nader used the mega backdoor Roth to contribute up to $69,000 a year into his 401(k).The strategy involves making after-tax contributions to a 401(k) and converting them into a Roth IRA for tax-free growth.