To elaborate, it’s really easy to forge “regular” coins and really attractive to forge high value coins.

For example, the 1 British Pound coin was, before the redesign, widely forged:

As of March 2014 there were an estimated 1,553 million of the original nickel-brass coins in circulation,[6] of which the Royal Mint estimated in 2014 that just over 3% were counterfeit.

(Note for any languages that use the comma as a decimal separator: 1,553 million is referring to 1.5 billion)