The Democrats have a long history being masters of election fraud. Famously they stole the 1960 election with LBJ fraudulent producing votes late in the count in Texas and illinois to put JFK over the top. They tried to steal 2000 but were successfully stopped. State and local elections all over the country they have routinely committed fraud in over many decades.
They think when they and their media allies keep repeating the mantra “fraud is rare” over and over again, they’ll get people to forget their history and believe that.