In Trading, there are two categories of people, those who want to increase their bitcoin volume, and those who want to increase their dollar volume. Which one do you prefer?Why?
For me I prefer to increase my Bitcoin, why simply because it has more potential to grow you'll compare to Fiat.
For me, raising your Bitcoin also means you want to increase your Dollar or maybe the fiat you are using in your country. I can say that since the money you will be getting from holding or trading on Bitcoin is dollar or maybe the fiat.
You don't need to pick one on these options since you can do both. Even if you do one of these things the other will not be affected since it is connected. As long as you have fiat, you can invest on BTC, if you have BTC you can just sell it for Fiat.