It is because they can see USD form than bitcoin form and they already used USD a long time ago. They still prefer USD to bitcoin in their daily because besides that, they get an easiness using USD because USD is accepted in all countries while they can not use bitcoin in all countries.
But some people realize that bitcoin can be used for transactions and also as an investment so they prefer to use both USD for their daily life and bitcoin for their investment. Those people will have a chance to change their life because they can prepare their life for the future.
In simple terms it is like that, USD is still one of the benchmarks for most people because as you said, USD is one of the global currencies that can be used anywhere and anytime, so they always rely on it.
In contrast to bitcoin, which is only in the scope of crypto, as well as several countries that have adopted and legalized payments via bitcoin.
but zones like this if possible should be left as soon as possible if you really want to be in crypto. because indirectly if you still rely on USD you will only panic when the btc correction occurs like it is now