I'm very interested to see the absolute expenses and income. Since server hosting is very cheap these days, they are probably not making a lot of money? Or they are paying too much for hosting?
RSS readers are quite resource intensive. They need to continuously update feeds (even when you're not using the site) and when you reading they need to remember each post you've read. It's write heavy load that most databases do not handle well. So you need to shard and use more servers even with comparatively small number of users.