If you were fortunate enough to purchase one BTC for $1 and stored it in a cold wallet and then purchased a 2nd bitcoin on an exchange like Coinbase for $100,000 and then sold it hours later for $100,001 according to the US government your taxable gain isn’t $1 it’s $100,000. Using BTC to purchase something without converting it back to fiat doesn’t exempt you from capital gains taxes. Therefore until legislation changes or the government completely fails it’s a mistake to use bitcoin as a means of exchange over fiat unless of course you like to add a self imposed tax on yourself.