Hmm... If the cost of X, say a home, goes down, by say 20%, from AI (robots?) replacing human labor then how does that benefit those left unemployed to achieve that cost savings? Will we then pay non-workers the same as workers? More importantly, how will we determine who among us is to be which?
The market tends to seek an equilibrium, whereby the desired prices of both buyer and seller intersect. So if houses become unaffordable and unbought because of the aforementioned unemployment, then their price will automatically go down. Otherwise, what's a homebuilder going to do - build a home using his robot, and just sit on it?
What will happen during all this buyer-seller price-seeking, is a change in the way the robotics technology is applied/implemented/used.
That initial high-tech homebuilder you mentioned will only achieve the 20% reduction in the cost of construction, and won't be able to get adequate demand for the homes he gets built.
Somebody else will change the way the robotics/AI is used in the homebuilding, so that he achieves 40% reduction in the cost of construction. Somebody else will achieve 60% reduction in the cost of construction. Etc, etc.
But for these changes to happen, the robotics/AI has to at least start getting used in this sector.
The above is merely an example in automation - I only posted it because you mentioned homebuilding - but Artificial Intelligence is more about giving machines the smarts to deal with the complexities of the real world. There are related component technologies, like machine vision, optical recognition, voice recognition, LIDAR, etc, which give AI the tools it needs to grapple with the unconstrained real world.
The driverless car is an example of a machine performing a complex task that would normally require humans to perform. But of course, a driverless car can work 24/7 - it doesn't get tired, or sleepy, its reflexes don't degrade, its judgement can be continually improved just by learning from past data, and processing hardware will continue to improve each year, unlike the human brain, so that performance improves.
Stuff like machine vision may have started out being used in more controlled places like factory environments (eg. sorting parts or spotting defective ones on a conveyor belt), but obviously they're now increasingly moving out into the uncontrolled real world.
Perhaps battlefield applications will be the real stress-test that will force AI to evolve much higher levels of performance, so that it will be much more ready for ordinary everyday life. On the other hand, the more recent trends have seen consumer-level computing technologies advancing faster than military ones, because consumer applications are far more widespread and active than military ones.
But the more the technology advances, the more cases it will be open to use for, thus increasing the spread/scope of its usage, thus giving more opportunities to evolve/improve, including via machine learning.