politics

Whiskey, and in fact all spirits, only age while in casks. Once they're bottled they stop aging and stay as they were when bottled. With extremely old spirits you'll maybe see some sediment fall out of solution and whatever slow reactions happen with the residual tannins, maybe some photochemical stuff if left in the sun.

Price in older spirits comes from two places:

1. It's expensive to store aging spirits in their barrels because warehouses cost money to run and the spirit is going to squat there for years and years and years before use
2. The longer a spirit ages the more evaporates. There's a lot less material available for a 20-year than a 5-year despite taking up just as much space to age.

Any additional dollars come from moneyed assholes wanting to flex on each other by having famous rare vintages on their shelves