Why is this sad? The Classic Car market doesn't care about our feelings.
Search 1970's Mazda RX, or late 80's Toyota AE86 or Supras. 35 years ago I could buy decent RX3's for $2500. Can barely find one today in the same condition for $50k. Am I sad? No! I'm happy for those that cherish the cars they like.
About 50 years ago one could buy all-steel Model A Fords for under $500. Running. With a bit of rust. A former colleague of mine bought one - running, rego'd and easily WoF'd - for $50 in 1969. How much must you now pay for a barely-complete, unregistered, non-running all-steel Model A Ford? $25k? More? You've got vintage restorers, Rodders and custom car builders competing for steel tubs.
Classic car market candidates all feature advanced age, increased demand, diminishing supply, increased competition for the desireable parts. This results in increased price. Price fluctuates with overall economic sentiment and prosperity.