The most expensive thing in systematic trading is often not a losing strategy. It's the two years you spent not being in the market.
Everyone underestimates this because time doesn't show up anywhere in your P&L. A blown account is visible and painful and you learn from it fast. Three years spent building a custom machine learning backtest engine, a feature pipeline and an ML framework before you've placed a single live trade costs you *far* more, and the damage is completely invisible.
And the cruel part is that the building genuinely feels like progress. You're learning, you're solving real problems, you're getting better at something. But you're getting feedback about your code, not about the market. You only get it by being on the field.
Meanwhile the thing you were going to build usually already exists in a simpler form for almost nothing. If you want trend, start with a basic 12 month lookback and a monthly rebalance. That's your first sleeve done in an afternoon, live, compounding, teaching you things. Then every afternoon after that goes into the second sleeve, and the third.
Five boring strategies stacked together will beat the one brilliant one you're still building, because their drawdowns land in different places.
So before you build anything, ask what you can do *right now*, with the tools you already have, that is likely to make money. Do that this week. Complexity comes later, if the simple version genuinely can't harness the edge.