How come people and media are usually nostalgic about things from three decades ago?

So in the 2010s, I've noticed there's been a lot of nostalgia for the 1980s in media like shows or games. Even though I'm a zoomer, I'll admit that 1980s look pretty interesting and cool. Now it's the 2020s, and I've noticed that 90s nostalgia has increased in today's media then I remember during the 2000s when I was in elementary school, there was a lot of nostalgia for the 1970s in media with SpongeBob as a well known example. So out of curiosity I decided to examine if older media had nostalgia for things 30 years ago. A lot of 1970s media had nostalgia for the 1940s like Star Wars being heavily inspired by 1940s movies or Indiana Jones taking place in mostly ww2. A lot of 1980s media had a lot of nostalgia for 1950s media, and taking inspiration for the 50s. Then the 90s which was known for a lot of great cartoons, many of them seem to see 1960s as the golden age of cartoons and something to aspire to as inspiration.

So how come it's common to see media have nostalgia for things 30 years ago?