The tensions facing this Earth and species won't allow those expenditures.
The disruptions caused by global warming, the lack of food and fresh water for an exploding population, the money spent on wars, the unwillingness to work together (see Republican response to UN resolution on disability and talk to me about reason, cooperation), the terror experienced by the US when asked to be a part of something it doesn't completely control, the waning influence of the US in the world, the need for energy to be used for the welfare of those here all work together to prevent any Mother Earth support of a large colony anywhere else.
We will support roughly 4 million troops and 4 million prisoners, but we will NEVER be able to support 40,000 folks on Mars. We aren't going to be around that long.