The main problems that young people face in Cornwall is a lack of a good range of decently paid jobs. It also doesn't help that many of our county councillors are utterly useless.
I have lived here for over 20 years, and used to holiday in Trebetherick long before that as my family had a holiday home there! Trebetherick is interesting as it is now a popular wealthy middle class holiday destination, but it certainly wasn't in the 60s and 70s.
It really sprang up as a holiday home village in the late 19th century - when trains made it possible to come so far for a holiday. Before the holiday homes were built there wasn't really anything here!
To be honest I can't see the difference between holiday cottages and second homes - both mean there are insufficient residents to support vital local services and they will both be empty most of the year. If anything second homes are more likely to be used more I would have thought - many people come down to check on things, or come last minute because of a good weather forecast.
Most second homes of people I know were once family homes, parents have died and the children have kept it and share it with brothers, sisters, nieces and nephews for holidays and so on. Many are used for regular family gatherings, and are rented out for as many weeks a years as possible - usually to the same regular trusted renters.
People I know who have holiday cottages have usually converted outbuildings and use the rent to supplement income (although the returns are pretty slim for the amount of work).
Tourists are a vital part of the economy, and you have to adapt to make a living out of it. A friend of mine has a very successful business putting air conditioning into second homes because the fact they are closed up for so long causes all sorts of problems. People can also earn quite good money by offering concierge services.
It is sad to see the life sucked out of some places by second homes - Padstow and Port Issac were very different places when I was young, and it is a problem, but what would replace this activity in economic terms?
A tiny minority of visitors behave very badly, but otherwise they are welcome as far as I am concerned.