Yeah thinking back even further, it really began (no surprise) with the Boomer Consoomers when they were growing up in the 50's/60's. They were the first generation to grow up with mass-media and advertising targeted directly at them. Before that ads were largely targeted towards housewives (e.g. the original "soap" operas on radio) and more commonly touted the virtues/benefits of a better product, rather than buying crap you don't need just for the sake of buying.
Ads were targeted toward all groups, although housewives were the largest demographic for radio and later TV since they'd have the TV/radio on all day at home. In the evening/prime time slot there'd be advertising toward men like the infamous Flintstones cigarette ads (which was primetime TV at that point since it was basically like the Simpsons of its era). Advertising toward men would usually be seen in newspapers and magazines with a male reader base.
And I'm not sure if boomer consoomers really started it. While people hoarding useless things probably goes back to some caveman's bone collection, the modern mentality is probably a late 19th century thing which unsurprisingly is when the advertising industry and mass media started taking off. I can't think off the top of my head any examples, but I'm sure if you look through lists of bizarre trivia you'd read about people 125 years ago with a similar mentality we see today. I know by the 50s, the time that boomers were kids, you can already see adults spending money on odd trinkets like my 80-something grandmother and her collection of those little spoons which according to this thread is pretty common among people her age. Baseball cards might be the male version since those were often targeted toward adults (nominally) since they usually appeared in cigarette packets until too many players decided they didn't want to promote cigarettes so they switched to putting cards in gum packets instead.
The thing with Boomer Consoomers is that's when consoomerism started merging with pop culture. Like now it wasn't just a celebrity endorsing chewing gum or cigarettes or whatever, now he had his own TV show. Then you had shit like Elvis and the Beatles where it wasn't just music but an entire cultural trend (way more than like Frank Sinatra or whoever) and shit like the Monkees (corporate Beatles but meant to sell merchandise and advertisements to kids/teenage girls). Action figures came out in the 60s too which gave all sorts of new incentive to buy entire sets of things and keep them hanging around. The earliest trading card collections that weren't just bonuses like the cigarette cards or gum cards came out in the 50s and 60s too, promoting popular shit at the time.
This all set the scene for the 70s where consoomerism as we know it emerged. All of your favorite products would have a cartoon, toyline, and by the end of the decade a video game in arcades or Atari (i.e. Halloween, the band Journey, etc.). Movie-based toylines took off thanks to George Lucas and Star Wars. You had KISS deliberately encourage marketers to put their faces and name over everything to get this effect. Product placement really started to show up in movies where the characters would be eating or drinking some popular brand that paid for it, although this is probably most famous in ET (which was the 80s granted) which is why Reeses Pieces as a product took off at all.
Enough of a history lesson, here's some random boomer consoomer shit.
Reddit user buys largest Elvis collection in the world:
Wall to wall, floor to ceiling Elvis collection:
A much smaller Plebbit Elvis collection:
KISS ate this Redditor's room:
Funkopop crossover. I guess KISS is a little too boomer for Funkopop's target audience so there's only four KISS Funkos.
Some boomer stuffed a room full of Harley-Davidson memorabilia that added up costs as much as several bikes. There's more where this came from (
https://archive.is/CpjOF).
