I have never been terribly impressed by the Dyson Sphere idea. It would be inordinately difficult to make, and would tie a population to one sun, with the vulnerability that implies.
My thoughts are that a trillion rotating habitats would be far better. By the time a civilisation has reached the development level needed to build a Dyson Sphere, they would be mobile in their stellar system, and have effectively unlimited nuclear fusion energy based on deuterium.
Such a society would have little difficulty building a cylindrical habitat in stellar orbit, rotating for gravity, capable of holding a population of a million or more. When that is built, then build another, and another. The total population size is almost limitless. Each such habitat can glean water and minerals from everywhere inside the stellar system. If our own solar system is typical, then there is enormous amounts of each in comets, rings, moon, asteroid belts, Kuiper belts etc. A rotating habitat is, unlike a Dyson Sphere, totally mobile. If the star it orbits gets fractious, then it would be simplicity itself to head off to another star for safety. (Take a few decades, of course. But a self sufficient habitat, well stocked, would have no problem with that.) Or even hide out in the Kuiper Belt.
Building a Dyson Sphere is kind of all or nothing. There is no benefit in half a sphere. Yet each and every habitat built becomes a home. Much more sensible.
On the energy side, Earth has enough deuterium in its oceans to provide enough energy at current rate of use for a billion years. But Saturn's rings have 30 times as much water as Earth's oceans, and there is evidence to suggest that this amount is dwarfed by what is in the Kuiper Belt. And Jupiter, of course, has so much hydrogen as to dwarf all the hydrogen in the rest of the entire solar system (excluding the sun). Energy in extraordinary abundance!
So am I correct? Is the Dyson Sphere idea silly compared to a vast number of mobile and rotating habitats?