Recently I heard that many years ago a number of stations sold a lot of season tickets for very short journeys, although very few journeys were made. The example I was given was Attercliffe - Sheffield. The reason was big discounts given on tickets that could only be bought by any season ticket holder, the likely savings greater than the cost of the season ticket.*
That might have made the first class Penzance - Wick return attractive. In those days there would have been first class available all the way.
Today a return standard class return from Penzance - Wick with railcard seems to be possible for about £450. With split ticketing probably less. Quite a lot of changes and night travel, but doable. I suspect it's been done and could be a rail enthusiasts challenge.
* About 30 years ago I spotted that if you sent in wrappers from Colgate toothpaste they'd return a voucher to be given Premium Bonds. It was too good to be true, but it was true. Buy £5 worth of toothpaste and be given £10 in Premium Bonds, a no brainer deal. That toothpaste must have lasted us over 5 years!! Marketing people can get things wrong, or maybe they get it right; these sort of delays get us hooked.