> I'm aware of the timeframe involved with even starting a Dyson Sphere.
A Dyson Cloud (a more accurate description than "Sphere," as "Sphere" implies a solid shell) can be begun right now, with a lunar metals infrastructure. O'Neill colonies are the first step.
Yes, the cloud is a better description. O'Neill colonies are a step along the way as is the exploitation of the resources of the moon and captured asteroids. But, in order to accomplish this we need the right tool - a space elevator. A worthy goal is the construction of that tool.