It's inflation, simple as that. The US left the gold standard at the exact same time that productivity diverged from wages. Coincidence? No.

Pretty much everything gets more expensive, with the outliers being tech which has gotten much cheaper, mostly because the rate at which it progresses is faster than the rate at which governments can print money. But everything we need to survive, like food, housing, etc, keeps getting more expensive. And the asset class get richer as a result.