Lyn,
It's just a matter of having the hoarding space to store these things, and then having the time and inclination to sell them on eBay or at auctions many years later. When I came out of the RAF in 1957 I had hundreds of valves, mostly new, and the value of each at that time was a few shillings. Now very much in demand and worth a small fortune, and most are now made in Russia or similar countries. I've moved house many times and finally, nearly 16 years ago, made the move out to Crete. This final move made me get rid of almost everything of value that I hadn't already disposed of - international moving is not cheap. I'm glad at this age that I don't have dispose of a lot!
Maurice