By selling what they’ve built? They don’t make any money while building. I don’t expect you to read all of the links I offered, but at least skim them lol. Slowing completions and reducing starts keeps per unit profits high, as the alternative, cutting prices and accelerating completions and increasing starts boosts revenue but reduces per-unit profits. Small construction outfits have no choice other than continuing to work, but the larger ones can just slow expenses and refuse to move on price until they’re purchased.
Capitalism just tries to make as much money as possible. That’s only a benefit when human well-being and profit are aligned, and otherwise just inevitably results in monopolies if we let it.