Because they, along with 92% of the rest of Spain, agreed in a referendum on a constitution that calls on the "indissoluble unity of the spanish nation". Because this referendum was illegal under that constitution. Because the rest of the country they are part of is affected greatly by whether they stay or don't stay; those rural parts of Spain need support from Madrid, Barcelona, Valencia. Because it could be the beginning of even further calls for independence from other regions. Because they already have autonomy, face no repression economically or otherwise, aren't on the back of any war etc. Because in the mess that is the world at the moment, the last thing we need is more division. Because polling suggests that actually, Catalunyans don't actually want independence.
Who cares if Spain brakes up if people democratically decide to leave.
Does a vote to agree to a constitution mean it stays the same in perpetuity? Constitutions and laws change and evolve on all matter of subjects.
Forcing people to be part of a country they don’t want to be part of is nothing but colonialism. And while I agree that seems to be a lot of division in the world and we don’t need any more it’s easy to say that when your not actually affected by that particular struggle.
If most Catalans don’t want independence, then the Spanish have nothing to worry about by a referendum I’m which case it should go ahead.
