The trick is that there are a bunch of mattress companies on Amazon selling really cheap foam mattresses (~200$) that are basically the same as Casper. But Casper jammed a ton of money into branding and marketing, so probably has great margins on their products. Foam mattresses as a product are getting extremely cheap and the quality is really not bad. I have a cheap one and honestly like sleeping on it more than 1200$ spring bed I had.
"“Barriers to entry are low, but barriers to profitability are high,” he said. “It doesn’t take that much to design a mattress, a marketing campaign, put up a website, and have one of these big companies like Carpenter do the fulfillment for you,”"
The majority of bed-in-a-boxes outsource their manufacturing...They’re literally calling around to producers saying, ‘we need a finished product and here’s what we think it should look like.’ Sometimes, they don’t even know what they want it to look like...Most of the outsourcing is to just four major manufacturers
I've had others staying in our guest bedroom love it too and go out and buy one. At this point, with a number of moves and growing family, I've bought something like 5-6 of them.
I think Costco sells the same mattress under Novaflex or a similar name but at a slightly higher price point (the Amazon price varies quite a bit on the Sleep Innovations mattresses -- check CamelCamelCamel on it if curious).
I've moved a lot in the past few years, and each time buy a new mattress. Each time I've bought on Amazon, and to be honest, never had one I hated. Brooklyn Bedding, Zinus, etc. My favorite so far I took a complete gamble on and didn't expect much, but wow was I impressed. I have only had it 6 months so can't speak to its longetivity, but I sleep like a baby. It's a 'Revel' brand, here https://www.amazon.com/gp/aw/d/B07CZWQ97P/
My kid sleeps on one, while I sleep on a Casper, so I can compare side by side. They're more or less the same thing for all intents and purposes, except Zinus is 1/4th the price.