Only certain Hasidic groups oppose Israel, including Satmar Hasidim (over 100k followers), and Neturei Karta (fringe, only about 1k supporters). That's less than millions, and a minority within the Hasidic world.
Theologically, they oppose it based on an interpretation a Talmudic passage saying that establishment of Israel has to happen after the coming of the Messiah.
Additionally, there are a lot different denominations of Jews within Israel, some of whom have more pragmatic views. But a significant, politically influential minority believes in their duty to govern all biblical land.