Yeah sure, if we suppose that we have nearly infinite resources (energy and material and science to propel billions of humans off the Earth and across the galax

Yeah sure, if we suppose that we have nearly infinite resources (energy and material and science to propel billions of humans off the Earth and across the galaxy), we have no short-term resource problem. However we're already constrained (average OECD countries energy availability has been falling since 2006), so you can't exactly hand-wave the problem away.