They brought it on themselves...
If it wasn't for greedy locals selling houses to outsiders, there'd be no housing price problem in any of the tourist areas that bleat on about it - Cornwall, lake district or wherever.
You can just imagine the scene at the estate agents:
Cornish Local: "Both my parents are now dead, they left me their house so I'd like to sell it please"
Estate Agent: "OK, how much do you want to put it on the market for?"
Cornish Local: "How much is it worth?"
Estate Agent: "Well, there's this bloke in London who wants it for a holiday home, he'll pay you £300,000"
Cornish Local: "Blimey, my mum and dad only paid £500 for it, but I suppose that was a long time ago. Hang on though, seems a bit of a waste the place only being used for weekends. Are there any local people looking for houses?"
Estate Agent: "Oh yes, there's a lovely young couple, just got married, looking to move into a place of their own. Both of them are Cornish, work and live locally"
Cornish Local: "Awww, that's nice. How much are they looking to spend?"
Estate Agent: "Well, he's a mechanic at the local garage and his wife's a teaching assistant. They can afford about £100,000"
Cornish Local: "Sod them then, I'll take the £300,000 from the stupid emmit, pay off my mortgage and buy a speedboat."
Nobody is forcing Locals to sell houses to outsiders, they are choosing to do so because they get more money that way.