The Marshall Plan was not a global wealth redistribution scheme. It was one government forcing its citizens to subsidise other countries. Not only is getting all governments to adopt this policy impractical, even id were practical it would be highly problematic because it has major human rights implications. Forcible redistribution violates people's privacy and private property rights.

Maybe the best argument for creating an off world colony is to give people somewhere to escape to from authoritarian ideologies like yours.