Is Olam Ha-Zeh sustainable?
Probably not – but that has never bothered us too much. Our tradition is to define a happy person as one who is content with what they have. Historically as soon as Yidden made enough to survive, they cut back on work in order to focus on more important things (Torah and mitsvos).
If you compare the standard of living of frum Jews in America in the 21st century, to what almost all frum Jews experienced a few centuries ago, you will realize that even beggars live better than the typical Baal ha-Bayis in the past .