I bought a Casper because I needed a new mattress, and I was already aware (thanks to ads they ran incessantly on my favorite podcasts) that there was a company with a quick and simple solution to my problem. I did a few minutes of research to verify that people actually liked the product, then I bought one. Yes, in the few minutes I spent doing my due diligence, I found a ton of other companies that were also selling foam mattresses over the internet, and many of them were cheaper. But the quality and wide distribution of Casper's marketing suggested they were a real company with substantial resources, and would likely be around for a while to support the product, whereas the other companies seemed like much smaller operations.

I have certainly switched brands or variants of laundry detergent, toothpaste, deodorant, etc. because I saw an ad that let me know there was something "better" to try out.

The common denominator here is that these are products I don't care that much about and am not going to invest that much time in researching. I don't really want to spend much time thinking about mattresses or toothpaste, and so I'm perfectly willing to rely on advertising as a passive way of getting information about what's available.

On the other hand - I would never buy a smartphone, or a laptop, or a car from an advertisement, because these are things I'm passionate about and I already know the market and what fits my requirements.