All of that mass on Venus is a bit of a tease though, because it will be almost impossible to mine anything on the surface (just too hellish, and you still have to pay the launch costs to get it up to your colonies).
Well, not really: we managed to make complex landers with scientific equipment that survived for about an hour back in the seventies. I'd expect we'd be able to do better with mining equipment (which would probably be very similar to deep sea oil rigs). Also, the colonies are not orbital, so pulling up material would not require a launch: pulleys on balloons would suffice, like a lot of logging companies today, but on a somewhat larger scale.
The value of mass is certainly not to Earth, of course. There's no plausible scenario where we expand habitation to other planets for financial gain. The value would he having it close at hand for the colony.