My intuition is that as people's standard of living improve, bedding is one of those things that gets easily overlooked when you can't afford it but is somewhere investing some "real" money returns a good result.

I went from using the bed from my parents' house (which was a hand-me-down) to a dorm bed (briefly) to the absolute cheapest thing I could get my hands on that wasn't stained brown or covered in bugs. It wasn't until I was relatively successful and making ~$80k / year that I felt like it was reasonable to invest in a nice mattress, and even then, I came to the conclusion that the "mattress store" beds were way overpriced and had little to differentiate them.

I ended up with a memory foam bed off Amazon. It was ~$200 for a queen and I've had it for about five years. The biggest issue I have with it is that the fabric seems to take stains more readily than my previous mattresses. Comfort-wise, I'd put it on part with a $1,500+ "mattress store" brand, so I'm happy replacing it every few years and passing my old one on to someone who doesn't have a decent one. In fact, it's getting to be about that time...