The concept of 'paying down debt' vs 'investing' always gets framed as a binary choice, but it rarely has to be.

If you have $1,000/month in discretionary cash flow, you don't have to choose between investing all of it or paying down debt with all of it. A simple split — say 60% to investments and 40% to debt above the minimum — lets you do both.

The behavioral benefit of splitting: you're making tangible progress on two goals simultaneously. Paying only minimums on debt while investing everything can feel irresponsible to some people. Investing nothing while attacking debt can feel like you're missing the compounding window.

The split doesn't optimize the math exactly, but it's not far off from optimal in the 4-7% debt interest rate range. And a strategy you'll sustain for 5 years beats an optimal strategy you'll abandon after 6 months.