I don’t really understand the motivation of Catalan separatists. They are part of a modern, stable, rich and highly developed country which AFAIK lets them live

I don’t really understand the motivation of Catalan separatists. They are part of a modern, stable, rich and highly developed country which AFAIK lets them live autonomously, doesn’t try to suppress their language and culture, etc. If they successfully become independent (which tbh seems extremely unlikely) wouldn’t the best case scenario be that things are almost exactly the same as now? Out of the three main separatist movements in rich countries (Catalonia, Scotland, and Quebec) this is the one I understand the least, and also seems the least likely to succeed because the Spanish state is absolutely not willing to entertain the idea at all.