This only "builds real wealth" for one person. For the larger system consisting of all 6 people, it's a net loss (the interest payments are still leaving, upwards). We've built a financial system where it is in everybody's self interest to make everybody else worse off.
The positive sum progress from the economy was enough to outrun this setup when there was abundant energy and foreign countries to colonize, hence the focus on "growth". But that era is over, and we're now stuck with a black hole of debt that still needs to be serviced...