This is mostly click-bait.

Things have always gone in and out of fashion. When I was a child, everyone collected carnival glass and Florence of Pasadena figurines. By the time I was an adult, nobody was really interested. Certainly not new collectors. In the 1960s, china dolls were very popular. By the 1980s, doll collectors had moved to French Bisque and the price of china dolls fell. Then china dolls came back into fashion and prices went back up.

Almost NOBODY collects what their parents collect. The children will collect, but not the same things as their parents. They want their own identity. Which means that yes, someone else's children will collect your parent's Waterford, Asian antiques, etc. .

Collectors buy in a price bubble. Once something's value goes out of that bubble, collectors will move on to collecting something else. This is one thing that dealers do not get. It is not in their best interest to have constantly rising values.

The instant collectibles of the 1980s were fraud. In many cases, Steiff for example, the number of the limited edition was actually larger than normal production run. Numbering was a joke because often the early pieces were not painted as well as later pieces. "Firing days" was also a fraud. The Chinese porcelain factories can fire 1000s of pieces in a single day. Rarely is anything purchased new as an investment going to increase in value, including Billy Beer, Spiro Agnew watches, and the Playboy issue with the Jimmy Carter interview. Everyone had the same idea as you did.

Rare will always have value. The Hummel "Little Velma" is still in the $2,000.00 range even though prices for other Hummels have dropped.

Value does not equal interest. The notion seems to be that if an item isn't worth four figures, nobody is interested in it any more. This is false. I know several young people in their 20s who are fascinated by all things 70s. They collect Joan Walsh Anglund, Determined Productions items, Gemma Taccogna, Lucite grapes, etc. The value tends to be $50.00 and under.

Just because the price has dropped does not mean there is no market. The price of Raggedy Ann and Andy items and Disney items have fallen greatly because the is no longer the competition form Japanese collectors. There is still a market for good examples even though prices have fallen.