Not every project/product in the world needs the capabilities of the cloud.

Companies go through different growth phases usually heroku like services --> aws/azure/google style cloud usage ---> baremetal self hosted style services, their all good depending where you are in your journey, for them it sounds like they decided their at the stage that self managed baremetal makes sense for them. ( the whole rant about everything goes through aws, companies that take advantage of economies of scale will always cause centralization, dont think we will be able to get away from that )

There's some stuff you pay indirectly with cloud (sec ops, another building waiting, compliance, recruitment) which may make cloud good/bad fit. One challenge remains that there's limited amount of discount ladder per service which makes for some scenarios PaaS look a bit expensive. BoM is cpu and memory for large part and volume buying helps margins.

One thing I've always loved and respected about Basecamp is how they are not shy about going against herd mentality and do things differently if it works best for them. For example how they don't do daily standups for the sake of it and favour asynchronous communication or how they were a remote company before it became fashionable because of covid. So if this works for them, I am pretty sure they have done the math and thought about it thoroughly and I completely respect them for it. Just because something works for many companies, doesn't mean that it works for all companies - so good on them! I just wonder if they considered smaller cloud providers, GCP and AWS are particularly expensive, but there are smaller tier providers that are much cheaper like Linode, perhaps it wasn't worth the risk for them.

I agree. I have always respected them and their takes and opinions on various matters over the years, even if I disagree with them. It's refreshing to hear differing views and opinions and someone questioning the "status quo."