The butterflies are indeed dying though.

https://biologicaldiversity.org/w/news/press-releases/congress-urged-to-spend-100-million-to-save-monarch-butterflies-2024-05-13/

The latest annual count for the eastern monarch butterfly population was the second-lowest ever recorded. The population declined by nearly 60% from the previous year and is only 1/6 of the size needed to be out of the danger zone of migratory collapse. The western population of monarchs, which famously winters on the California coast each year, remains at just 5% of what it once was