system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: If whiskey only ages in wooden barrels, why aren't whiskey bottles made out of wood instead of glass?
gpt
I have a small barrel that I've used to age spirits. A wooden whisky bottle is undesirable for many reasons:

1. Cost. Barrels are expensive. You wouldn't want to buy a $20 bottle of whiskey in a $50 barrel when a $0.50 bottle would do the trick.

2. Rate of ageing. Whiskey is aged in barrels that are tens of gallons. It's sold in bottles that are less than half a gallon. That means relatively more barrel surface area per gallon of whiskey. This is important because of point 3...

3. Overageing. More isn't always better. Different flavors come out of the wood at different rates and you want some flavors more than others. If you leave the whiskey in a barrel too long then it'll pick up the wrong flavors. With a tiny barrel this can happen much much faster. 

4. Sediment. Some of the barrel flakes off; it's been charred on the inside and then soaked in alcohol. Bottled whiskey has had this removed, either by settling or by filtering.

5. Volume loss. Barrels don't seal tight. They lose some alcohol and water to the air which changes the alcohol content of the contained spirits. 

When you buy a bottle of whiskey you're paying for the stuff that went into the unaged spirits, the time and space it took to age it, and the expertise of those who aged it, making sure that it picked up the right flavors and made it to the right alcohol content.

If you turn around and stuff it into a barrel to sell then that expertise goes right out the window and the price goes through the roof.