DHH on leaving the cloud for their own hardware. Not exactly a new idea – famously they’ve been preceeded by the likes of Dropbox and GitHub – but novel for a company as small as Basecamp. He says they spent half a million on servers, but stand to save 3x that at $1.5 million every year.
The biggest thing that comes to mind is on-call. Back at iStock in 2011 our ops guys made all hours trips to the datacenters with depressing regularity, so while it made self-hosting possible, the cost was much higher than just the hardware bill. But that was a long time ago, and a lot of it was probably self-inflicted, so maybe things are easier nowadays.
The next thing that comes to mind is blob storage (e.g. S3). It’s such a useful abstraction, and although open-source alternatives exist, it’s a lot. Would even a company hardened in their intention to self-host turn their back on it? I would guess not.