With fiat money, we do not have 100% control over our assets. But Bitcoin is not like that and we can freely trade it anywhere in the world without the control of third parties.
Actually it's true, but most of people hold their Bitcoin on centralized exchanges... then it's no longer 100% control over your coins. Lack of knowledge and doesn't understand what is custodial or non custodial, they thought their asset is 100% safe.
Their will be huge variations in the price of fiat. Even take U.S dollars, their is some high variations as compared to INR. So it's better to inverse on a crypto for the longer period. Keep on addition investment at all the dump in the trusted crypto. When the market up, you can hold for next bull run. It will not same dump for a next dump. Only the profit will get from the nature of curve chat.
Not disagreeing your opinion, but if Bitcoin is treated as investment asset and not a currency, which you used for daily expenses... it wouldn't make Bitcoin will completely replacing Fiat in the future. I'd say Bitcoin isn't a better option than Fiat and Fiat isn't worse than Bitcoin because both of them work on different purposes.