My belief is because Binance Smart Chain has a system to modify its GAS according to Changpeng Zhao's orders because for GAS this can be a problem if the GAS costs are expensive in the future.
As far as I know, Binance Smart Chain has a centralized system, I don't know what the system is, but what is certain is that the GAS costs can be modified by Changpeng Zhao so that in the future, even for network density, GAS costs will not be expensive.