If we look at our planet, we should realize that fossils and nuclear power are limited. Aside of the quantitative limitation, we get to feel the negative green-house effects now, making alternative energy sources even more urgent.
The only real long-term source is the sun. We HAVE to (completely) switch to sun energy within the next 100 years. This will require huge photon harvesting facilities. For now, covering our deserts would be enough. But what if our energy requirement increases 10 fold? The more energy we have, the more people can have steaks and luxury.
In the SECOND we reach the point of energy limitation on Earth, we will expand our photon harvesting facilities into space, close to Earth. This will grow with generations, so will technology. The gigantic amount of energy daily shining onto Earth is still ridicously few compared to what the Sun radiates every second. The photon harvesting layer will shrink, become more efficient, harvest more wavelengths (maybe even just a single atomic layer) and routed to central cores where it is collected and sent to Earth or the future intelligence habitat. Even if it is just a mirror, redirecting the photons to a central core, which routes it close to Earth, where it will evaporate water - or whatever much smarter ideas our future generations will find.
And this is what we could do now with our technology.
The infra-red issue, imho, is based on current technology level. No light enters the depth of the ocean because life evolved to build photon-recepters of all wave-lengths, even the less fruitful.
Taking this into consideration, every maturing civilization WILL inevitably produce Dyson spheres at least transiently. We already started it! Just look at the solar moduls of the ISS, which are actually the beginning of a Dyson sphere.