#personal-finance

Compound interest is earning returns on your returns. It feels like magic because humans think in straight lines and compounding curves upward. The one variable that decides everything is time, and it's the one you can't buy back.

Two different questions hide under 'DCA vs lump sum' and most articles blur them. If you've got cash to deploy now, the data is clear: investing it all at once beats averaging-in about two-thirds of the time. But that's not the whole story.

The whole Roth vs Traditional debate reduces to one question: is your tax rate higher now or in retirement? The math is symmetric. The decision is a bet on future tax rates. For most people under 40 who aren't high earners, Roth is the default that ages well.