It's from the rapid exploitation of an asset. If I have a cow, I can milk the cow or kill the cow. If a cow costs $1, maybe I can get $5 worth of milk over the cow's lifespan, or I can kill the cow immediately and get $2 of meat. The man with $100 who buys all the cows in town and kills all of them doubles his money in a short timespan, but now there's a shortage of both meat and milk next season.