Objects that hold their value tend to be well-made and of good quality materials. Sadly, not a huge number of the consumer goods that reach us nowdays touch both those bases. In addition, examples of iconic products tend to age well if you keep them.
But the thing about antiques is they are ultimately the bits that survive from the past. If you have the space to hang on to all your toys, clothes, games, furniture and books then you're bound to bag some winners.
But most of us wore out our Biba, broke our Hornby, spilled hot drinks on our 60s teak sideboards and didn't have the staff to put them away in the spare stables.
So the rarity defines the surviving stuff as 'valuable antiques'.
I remember the junk shops on Regent Road i Salford in the 1960s where they were practically giving away mahogany furniture cos it was unfashionable and nobody wanted it. If you could have filled a van then and stored it, you'd be quids in now.