I think it might be that with increased prices, America is less willing to pay so much for mediocre-or-worse pizza. At least in my area, the chains seem to be suffering, but the places that sell good-or-better pizza seem to be doing fine.

Which makes sense, because there's much less of a price differential between the two now.

Frozen pizzas have gotten a lot better over time as well.

America is falling out of love with discretionary spending.

Pizza used to be $5 now it's $12 at LC

The quality of pizza has noticeably decreased over the years. People would laugh at the idea of Pizza Hut being a delicious, dine-in restaurant. Now it's fast, expensive slop. Keep cutting costs and quality until you go bankrupt.