It's difficult to scale an RSS reader as you could quickly start having to crawl orders of magnitude number of feeds more than you are now as you get more users

It's difficult to scale an RSS reader as you could quickly start having to crawl orders of magnitude number of feeds more than you are now as you get more users, if power users like your thing. I know because I worked at Bloglines. You're either going to need money or you will shut it down eventually.