My MIL once asked what purpose a cat had, if we did not have mice. The purpose was simply to have someone to love, that would love us back. Increasing the amount of love in the world should be more than enough of a purpose. Just as increasing the amount of joy in the world, by devoting yourself to whatever "silly" thing it was, is more than enough of a purpose. It's only those who are unable to measure these things for themselves, using their own hearts as rulers, that must fall back on societal dictates as poor substitutions for true measurements of worth.