Um the plural usage is right there in your quote.
and bitcoins (with a lower case b) to label units of the currency.
Do you also say I won five hundred dollar or man prices in the UK were expensive that [...] was 10 pound.
It is unit
s of currency thus it is plural. The only time the unit
s of currency is singular is when it is one unit.
That will be one dollar.
That will be one bitcoin.
That will be two dollars
That will be two bitcoins.
Pound is already both plural and singular.
£10.50 is pronounced 'ten pound fifty' (rarely pounds) - but it's ok to say 'ten pounds and 50 pence'
Interestingly 1p is pronounced 1 pence, but the coin is referred to as 1 penny.
2 pence is 2 pennies if there are literally two 1 pence coins, or 2 pence if it is a 2p coin.
ie penny has two plurals - pence and pennies depending on context.