People are people, while some are lazy or not suited to modern workplaces, most studies have shown people on assistance will take work if they can get it. Earthers will mine if they get the opportunity. The Belt will probably have an edge in terms of knowhow but Earth can catch up. A big part of any colonization is farming and Earth has a leg up there. Considering the shit hole Amos indicates most of Earth is most people will be clamoring to leave. Also they show some of it here with Naomi but a lot of Belters cannot live in 1G so not all of them will be able to just settle into a colony.