That is exactly what it is, old plain tribal ethnic nationalism of exactly the same kind you suffered in YU and Europe has suffered so much in the not so distant past. Or what we see now in Ukraine. It's pure evil, it only brings missery, destruction and suffering. It has already brought a great deal of harm to this society, now very deeply split in roughly two halves who detest each other. Big former catalan banks (La Caixa, Banc Sabadell) together with roughly 5000 companies left the region already two years ago. VW Spain has green light from HQ to move, if so decides, SEAT factory (biggest company in Catalonia) out of the region. Catalonia sells more to Aragón (1.5 mill ppl) than to France! The economic argument is out of the question, just a bait for the gullible, they don't even mention anymore. The whole thing is pure tribal hatred, they'd rather destroy Catalonia if Spain is also destroyed.I support HK protesters because they clearly want to protect their rights and freedom. It is doubtful whether Catalans (some, not all) are really fighting for freedom or for pure economic-tribal based separatism based on some old stories and emotions. Spain is not a dictatorship, the left dream of 'revolution' is anachronous, at least 50 years late. Half of Catalans are against independence. The economic issue is also questionable. There could be an argument made that Catalonia is rich because it IS part of Spain, and that it would suffer economically in case of separation. They would need to apply for EU again and surely the rest of Spain would veto them. Big banks would probably leave. Uncertainty would last too long before possible, but not guaranteed stabilization - huge damage. There is no clear and agreed path to take the day after.
Of course, I understand that currently irrational rather than rational reasons prevail, like often happens around the world in different times. In this case, an unrealized dream of independence that would immediately lose all its charm once it happens to become reality.
I would support anything that would be legal and a result of peaceful agreement with clear way ahead. Because again, it is a democratic country not a dictatorship, and Catalonia enjoys a high level of substantial and real autonomy. Besides, I am personally for more unification (not forced but agreed) and less separation and borders. I hate borders in principle, although I'm aware they are inevitable and required.