If crypto takes over what’s the benchmark of stability?

Hi Reddit I’m new to learning about crypto and a question that came to mind is how the dollar generally stays level and gradually moves weaker or higher. If crypto such as eth takes over how will it be stable with such fluctuations? What happens to the general dollar if everyone is paying for things on the blockchain with crypto? Also what happens with general banking and how will they “police it” How will the government specifically be able to regulate it? Thanks for helping me understand:)