The subtext, which is absurd when made explicit, is that if not for tourism then those 100,000 people would not have jobs. In reality, jobs are created in response to demand, and you can obviously have arbitrarily large economies that are ~0% reliant on tourism and there's no reason to suspect Barcelona et al couldn't or wouldn't produce such an economy for itself in lieu of tourist demand.
Moreover, whenever someone says "XYZ brings money to the area" you need to look at who in particular it's bringing money to. It's not like this money is being dropped out of a helicopter uniformly over the area's people. It's largely going to a relative few businesses and property owners, who spend a fraction of it in the local economy, who itself spends a fraction locally and so on.
The jobs being created aren't high-paying professional jobs either, they are largely service jobs in areas too expensive for the workers to live. So they have to commute long distances on often underdeveloped infrastructure.
All the waiters and tour guides can't just re-train as semi-conductor technicians.
Even given time, it's not obvious that Barcelona or Spain has the necessary pre-conditions to be globally competitive in another industry that would bring in the same amount of dollars per capita.
It's an extremely ambitious, all-hands-on-deck type of national undertaking to shoehorn your way into something. Japan did it with auto-manufacturing in the 30s. East Asia in general with high tech manufacturing.
You can argue on the basis of principles that tourism is bad. The fact remains that tourism cannot be stopped cold-turkey without massive job loss as seen during covid. If you wish to stop tourism and preserve the well being of the people that depend on its income, then you need a plan for what replaces tourism and how to re-skill your workforce. There’s clearly no such plan in place.
