To force them to stay because other groups rely on money taken from them doesn't sound right. A similiar reasoning for keeping slavery existed in the US over similiar claims.
Slavery is an unfortunate comparison. Barcelona made a lot of money in the antiquity by being a main port in the slave trade that lasted until the XIX century it seems. Much later than other places.
The idea here would be more like: I rebuild your home, I spend a lot in infrastructures for you and now that you are rich you slam your door in my face.
The idea here would be more like: I rebuild your home, I spend a lot in infrastructures for you and now that you are rich you slam your door in my face.