Dollar-cost averaging: steady beats perfect

Dollar-cost averaging means investing a fixed amount at fixed intervals — every month, every payday — regardless of what the market is doing. Because the amount is constant, you automatically buy more shares when prices are low and fewer when they are high. Your average cost smooths out over time without you ever having to judge whether today is a good day.

The case for it rests on a stubborn fact about markets: the best days cluster right next to the worst days, usually during crashes, and missing just a handful of the best days over decades can cut a portfolio's final value dramatically. Timing well requires being right twice — when to exit and when to get back in — and nobody has a reliable record of doing both. A fixed schedule removes the decision entirely, which removes the two ways people most often hurt themselves: panic selling in a drop and waiting for a "better moment" that never feels safe enough.

One nuance deserves honesty: for a lump sum you already hold, historical studies generally find that investing it immediately slightly beats spreading it out over six to twelve months, because markets rise more often than they fall. Dollar-cost averaging a windfall is a compromise between optimal returns and the courage to act — and a compromise that gets money into the market at all is fine. But DCA from regular income is a different situation entirely: the money arrives monthly anyway, so a monthly purchase schedule is simply the natural choice, not a trade-off.

The practical move: automate the purchase on the day after payday so it happens before spending decisions exist, increase the amount with every raise, and never pause it during a crash — the drops are exactly when the schedule is buying the most shares per dollar.