Yeah I heard that all years before.
My SO is significantly smaller and lighter than me and when we moved together here in Germany we went to one of those "always sale"-shops that are all over. The guy talked to us for almost an hour. We tested mattresses and bought one we thought might be good for ~1000€. 2 years later(!), it already felt like it was getting worse, she was rolling on me, we had back pains and a year later we really needed a new one.
Fortunately a mattress seller became famous at the time in Germany for breaking the monopoly here and getting all the hate from the lobby. You know what he did? He sold the same mattresses everybody else sold but significantly cheaper. The margin was just ridiculous.
After being "banned" and not being supplied shortly after he started, he came up with his own mattress. 100€. Just foam.
We had it for ~5years now and I never slept so good before. The mattress have been tested as the best mattress on the market for many years here in Germany so it wasn't just us.
I know the US market is different because people seem to value ridiculous sizes and design over health and usability but this is what actually helps this scammy market to rise to those ridiculous prices.