Well, (somewhat tongue-in-cheek,) one of the defining characteristics of "good money" is that it is very inefficient to replicate!
(Several places online list "durability; portability; divisibility; scarcity; fungibility; and acceptability" as the key characteristics of "good money." Difficulty-of-replication pertains to the "scarcity" characteristic: if it's easy to duplicate, that makes it "bad" money, not "good" money.)
(Several places online list "durability; portability; divisibility; scarcity; fungibility; and acceptability" as the key characteristics of "good money." Difficulty-of-replication pertains to the "scarcity" characteristic: if it's easy to duplicate, that makes it "bad" money, not "good" money.)