There's a pretty tried and true cliché about multiples — that artists, for the most part, make them in order to make money.
Artists, like other business professionals [after all artists are professionals as loath as many are to admit it], pursue their practice with determination to make the best work possible, to disseminate their works widely and to receive appropriate remuneration for their labor in the form of gallery and / or museum exhibitions as well as an appreciable swelling of their bank accounts.