It is two sides of a coin: Bitcoin and fiats.
Bitcoin is created to give people freedom, be their own banks and be free from fiats. I disagree with people who say Bitcoin will replace fiats completely. It won't, in my opinion.
However, Bitcoin will beat fiats in terms of favorite in our social communities and in future, the younger people are, the more preference they tend to use Bitcoin for daily transactions.
bitcoin wont replace FIAT. agreed.
governments want control of their tax incomes and court fines and minimum wage laws. all of which make their FIAT viable.
if people could be paid in any amount, any currency and pay any bill, tax, or courtfine. then FIAT would lose its importance/necessity.
many first world countries governments will never lose their grip on their FIAT product. as having control over it means they can control their 'treasury income'
imagine if USA changed a law allowing people to pay taxes in anything else. people will try paying in baked bean tins and art and everything else. .. senators dont want to be paid a salary in 1month old rotten fish.
you cant then have the DOD buy tanks, warships and soldiers weaponry in peanut butter.
they want control of fiat to ensure people get paid in fiat which revolves around to being taxed in fiat which revolves around to paying senators and leaders in fiat, they are dependant on the circulation of their fiat.
bitcoin is a 'second option' where people are not made to only store value in bank accounts. but they can have more options of storing value in other assets.
US didnt drop the dollar, simply because some silicon valley coders were being paid euros for their 'remote work'. because the silicon valley coders then need to convert euros to dollars to pay U.S tax.
its the same thing with bitcoin. although you are paid in bitcoin or sometimes spend bitcoin outside the physical US(aka online)
people in america will still need to value that income/spend in dollars when doing their US denominated taxes. and convert bitcoin to dollars to pay said taxes
bitcoin is just going to be another option currency. like how americans treat the euro