Well, it's a hard thing to comprehend, from this vantage.
The last I knew of Barcelona was when it hosted the Olympics in 1992, rated a great success. Barcelona was just a city in Spain, as far as we knew at that time. What has changed?
The history that came long before the Barcelona Olympics included a Catalan nation absorbed into the larger nation of Spain.
Its like the Welsh nation and Scottish nation being absorbed into a larger British nation.
In more recent times, the troubled economic times we live in, people in Catalonia which has great wealth see their taxes going to other parts of Spain.
Its like a Texan watching their taxes go to New York and California or up in Canada an Albertan seeing their money go to Ontario or Quebec.