Key Takeaways Only 14% of participants max out their defined contribution retirement plans (such as 401(k)s), a Vanguard study shows. High-income earners are more likely to max out their 401(k)s, but even if you have a modest income, you can reach this goal. The power of compounding returns means you have a strong incentive to save as much as possible, as soon as possible. The reality of the U.S. retirement system is that most workers chronically under-save. Only about a third of non-retirees said ...