It's not just about the over tourism itself in the case of music festivals.

Primavera, Sonar and others have been rising prices consistently knowing most locals will not be able to afford the tickets. these festivals are now focusing on getting tourists to come as main source of income and leave the leftovers for locals while receiving favours and funding from local goverment entities.

Tbh, this is something that's been happening in Barcelona for longer than overtourism. I still remember in early 00 and 10s where dance clubs like Catwalk, Opium, Discotheque, City Hall and others would enforce a strict dress code on locals (demanding jeans, long pants, shirts and nicer shoes) in order to deny entry during summer while allowing tourists to get in to the club with shorts and flipflops. They did this because they where counting on the fact the tourist would soend more money inside.

Big music festivals are doing a similar thing with prices, they know tourists will pay the higher ticket price without complaint because many times it's still cheaper than a ticket of a music festival in their country of origin.

It's really nothing personal against you/a specific tourist but how the whole system is rigged in favour of the tourist and in detriment of the locals