Money compounding at a steady rate looks almost flat for a long stretch, and then it doesn't, and most people sell right before the part where it stops looking flat.
Take something growing at 12% a year. In year one that's a rounding error. By year five it's noticeable. By year fifteen the gain in a single year is bigger than the entire original amount you put in. The curve is the same shape the whole way through, it's just that the early part is too flat for a human eye to get excited about, and the late part happens after most people already sold.
Why the middle feels like nothing is happening
This is the part that trips people up. The middle years of a compounding position are, by design, uneventful. The business is doing fine. The stock is doing fine. Nothing is being written about it. That flatness isn't the strategy failing, it's the strategy working at the only speed it actually works at. If you need a feeling of progress to stay convinced you're on the right track, compounding will fail that test every single year until it doesn't.
I think about it like this. Compounding doesn't reward conviction, it rewards duration. That's not a satisfying thing to say out loud, but it's the honest mechanism.
- Doubling once from a small base looks trivial. Doubling five times in a row from wherever you ended up is not.
- The last few years of a long hold usually produce more dollars than all the years before them combined.
- A flat-looking chart and a dead position are not the same thing, and mistaking one for the other is the single most expensive misread in long-term investing.
The honest way to hold something for the long run is time-in, not timing. You don't need to catch the best year. You need to still own the thing when the best year shows up, which you can't predict in advance. That means the years that feel like the least are doing real work, they're just doing it too slowly for your nervous system to log it as progress.