Technically Goku was a farmer, but those parts were boring, so they never showed them. He probably did some odd jobs on the side too. Or maybe bulma just gave money to everybody… actually now they I think about it, chichi is technically a princess, they probably got a lot of financial help from the ox king.
They’ve received help from bulma but the reason goku became a farmer was because the ox king ran outve money sending gohan to college. Or it blew up with the mountain. Also winning the world tournament too. And then gohan married videl and money came from her dad. But in the grand scheme of things the man can bench press a planet, the only reason he should care about money is to buy calories