If I could guess well, the one that's assumed to have the possibility of going to zero is the dollar, and the one that can never go back to zero is bitcoin. Well, I'm a lover of bitcoin, and I'm also an economist. Bitcoin has a good purchasing power, and that has been increasing over the years as it has been gaining value more often as its popularity and adoption continue to spread.
 
I believe the dollar will never be equal to zero based on my own beliefs; it's just a reality that I have conceived in my mind. This is because the dollar is a country's local currency, which means they use it for their daily exchange of goods and services; they are being paid to others as salaries, and the same currency is being used to make payments for things we need to satisfy our needs and wants, so providing that the dollar use will still continue even if there has been dedollarization, which will make many nations not to use it again, the value remained attached to it.