NJ, blow ins used by the Cornish, many of their young folk had same problems as ours, once the properties were being bought up for these second homes, they had no chance because it sky rocketed the property prices.
i spent quite a lot of time down in Cornwall, some of the time with friends, and then the o/h, got to know the lie of the land so to speak
i know about mass tourism, and yes you are right, the economy in Cornwall would fall through the floor without them, but it's a double edged sword, as you must agree. That the more people you get, the more that will come, word of mouth for one thing, tell your friends how great it all is, the programmes that featured Cornwall, not just the latest Doc Martin but before that. Tin Mining was one of their biggest exports, however that has since more or less gone, fishing, not quite gone, but hanging on in parts.