The reality, however, it's different:
- Catalonia is a rich, privileged region of Spain, which has benefited enormously of a huge investment in infraestructure and industry in the last decades.
- The indepentist movement was fueled around outright xenophobia, accusing the central government of "stealing" Catalonians, attacking poorer regions of Spain (which are full of lazy, untrustworthy people).
- In the last years, the Catalonian government has shaped their citizen perception of history, promoting nonsense like "Catalonia is a colony of Spain". An easy to disprove, but widely repeated argument.
- The Catalonian government even forbade the use of Spanish to their civil servants. Which was fined by the EU.
For a long time, state politic parties and catalonian parties, profited from this absurd "us against them" scenario. Now it's really out of hand, and the central government has a lot of blame in this.
But I really failed to see why someone should have any sympathy for Catalonian independentism. It's certainly not based on any historical reality, their political and economic consequences are unpredictable (but I doubt that benefitial for anyone other than catalonian politicians) and it's illegal under any possible frame.
I guess you could justify it if you believe in this abstract right to self-determination. I personally would have held a referendum long ago. I still think it's both stupid and immoral (it's usually the rich regions that want independence, with similar arguments).