As company gets more and more efficient, they wouldn't need employees. But this would cause lesser money to be brought into circulation, thus eating up the companies earnings itself.
If the company wants more debt, they can go borrow from others (rich institutions, individuals etc) but this activity will not create new money. Thus, total money in circulation remains the same.
If an individual wants to buy a house, the house price will effectively be closer to the median affordable income of population. Thus, it will incentivize individual to produce more goods and services to reach median income at least. The only way to become richer is to produce more.The rich can try to buy more houses but it wouldn't be possible as much since leverage and speculation is much harder.