1: Bitcoin is scarce. There will never be more than 21 million Bitcoin. Fiat currencies have an unlimited supply, and all governments have often abused the ability to create new money. Every single fiat currency has lost value. While new Bitcoin is being mined, the supply schedule is fixed. The creation and thus the value of government money is completely unpredictable.
2: Bitcoin is freeze and seizure proof. No government or criminal can seize bitcoins that are properly secured. Bitcoins can only be stolen by improper security & practices.
3: Bitcoin is potentially anonymous. If proper privacy practices are followed, the owner of a Bitcoin wallet can remain anonymous. For example, while the balances of the richest Bitcoin wallets (holding billions of dollars) are known (aside from exchange wallets) their owners are anonymous. Hiding a fortune of this size is impossible with fiat.
4: The value of Bitcoin is not backed by debt. Fiat money is created when banks issue debt, either through loans by individual banks or the central banks purchasing bonds from member banks. The supply of money and economic growth is thus highly sensitive to interest rates, which central banks constantly manipulate for political gain. The outcome is endless business cycles and the systemic risk of currency collapse.
5: Bitcoin is independent of any central authority. Unlike fiat, no one is in charge of Bitcoin. Changes to Bitcoin can only be made by consensus and a lot of complex coordination by the Bitcoin community. While central banks are nominally independent, the reality is that politicians are constantly abusing the money supply (and public savings) to benefit their cronies.
6: Bitcoin is faster, easier, and more secure to transfer. A million bitcoin can be transferred for the same fee as one-millionth of a bitcoin. Bitcoin transactions are nearly instant and guaranteed to be irreversible by math and the laws of physics. No fiat payment network can come close to the speed, security, or finality of Bitcoin payments