There have been other threads on this topic, and I know I'm not alone.
The festivals you've named come at a cost, and few would be suitable for teenagers.
People have an idyllic view of Cornwall based on a week long holiday in hot weather. Living here is not the same.
The racism - I can count on one hand how many times I have spoken to a person of colour living in Cornwall in the last five years, other than the gents in my local Indian takeaway or the lady who runs the Chinese restaurant. Attitudes collectively amongst local residents towards POC are unreal - language that fell out of use a decade or more ago in other parts of the country are the norm. I won't write the words here.
It is a very white county. Sod all diversity. Aging population.
Job prospects are poor. We're a big county, with rural populations, heavily focused on the service sector. The service sector is staffed by young people who are employed on part time seasonal basis only. Wages are poor in all sectors.
Housing prices are out of keeping with local incomes.
Brain drain from the County has been the norm for decades.
It's all fact I'm afraid.