Why do some netizens refer to dollars as knives?

Because the Chinese word "knife" is the homophone of the English pronunciation of US dollar.

dollar

UK?['d?l?]?US?['dɑl?]?

n. US dollar

Phrases:

1. Zimbabwean dollar?Zimbabwe dollar

2. Half dollar?cent; US dollar nickel; Kennedy's head; half dollar

3. Straits dollar ? Lat currency; Malaysian and Singapore dollars; Lat Koh National Treasury banknotes

4. Malayan Dollar? Malayan dollar

5. dollar index? U.S. dollar index

Extended information

Synonyms:

1. greenback

English?['gri?nb?k]?American?['grin'b?k ]?

n. U.S. dollar; greenback

Example:

Many?people?see?gold?as?the “anti-dollar”, ?so?if?the?greenback?does?well,?they?have less?incentiveto own?bullion.?

Many consider gold to be “anti-dollar,” so if the dollar performs well , they have no incentive to own gold.

2. American dollar

n.[Financial] US dollar

Example sentence:

At?that time,?both gold and? silver?were?used to?support?the?value of the?American?dollar.?InEurope, however,?only?gold?was?used.?

At that time, both gold and silver dollars were used To support the US dollar, while in Europe, only gold is used to support the national currency.