Self replicating mining robots, likely clanking self-replicators, combined with low cost launch infrastructure such as orbital launch loops combined with skyhook satellites. This process would likely require several centuries but is theoretically feasible, and would be relatively easy to implant on Mars relative to the other rocky planets. Given Venus is the nearest thing known to Hell and Mercury isn’t much better.

As for resources, simply put the mass necessary to construct a Dyson Swarm and the fleets needed to colonize and dominate the galaxy isn’t going to be coming from earth unless we want to destroy our homeworld to do it. Considering earth is possibly the only planet in the universe humans can live on relatively easily, this is a bad idea.