Because there are laws keeping out competition. If anyone could make whisky, they would easily meet demand and price would be a small markup over costs.
You're forgetting that whisky is an analogy only, and like all models fails in many respects. Though the whisky made by people other than the government issuer may look & taste like whisky, it won't get you drunk like gobment whisky. The "drunk" is the "backing" of currency.
Except, going back to money, bitcoin is the nongovernment "whisky" and it does the jobs of wealth storage and international transfer far better.
Bitcoin co-exists with dollars the way sterling does. Bitcoin is great for international transfers and for things you want kept private. I don't accept its a wealth storage vehicle - I wouldn't expect someone saving for a pension to invest in bitcoin as the fluctuations would kill them.