The younger generations are absolutely not set on buying all-new stuff. Go in a thrift store and nearly everyone shopping there is younger than 35. Craigslist is much more popular among younger people.
The reason younger people end up buying shitty, disposable furniture is because they can't afford houses.
I am not sure about your idea here, I'm under 35, own my home, and insist on buying second hand furniture for vastly different reasons. I scour craiglist, thrift stores, and my local flea markets for vintage furniture, and have almost entirely furnished my small 2 bedroom house over the last 6 years. A big part of this simply deals with build quality and real wood. I know furniture built before 1980 tends to be real wood, and I'd much rather have solid wood construction over particle board nonsense that won't last 10 years.
My searching and insistence has required a lot of patience, but it's ultimately been worth it for me. My holy grail was a 1970's Danish Teak dining room table (w/ 8 chairs!) that someone locally was selling for $800. Anything modern that's of comparable quality would easily be well above $2500. As of now, almost everything in my house is from the 1960/70s, and made of real wood. I'm willing to spend the money on these things instead of junk from Wayfair.
The reason younger people end up buying shitty, disposable furniture is because they can't afford houses.