Why does George say the migrant workers who travel from farm to farm are the loneliest people in the world?

From the text:

"Guys like us, that work on ranches, are the loneliest guys in the world. They got no fambly. They don’t belong no place. They come to a ranch an’ work up a stake and then they go into town and blow their stake, and the first thing you know they’re poundin’ their tail on some other ranch. They ain’t got nothing to look ahead to."