My service has a lot of moving parts, all of which are distributed among a couple dozen different servers. Keeping the technical infrastructure running smoothly requires a lot of data visualization of server stats, database stats, web request stats, worker stats, user stats, etc. I have everything piped into a nice dashboard so we can see if there is anything odd happening at a glance. When things break (and they will) you need to know where to look first.
Having 5k users also requires time to help them with support issues. Users generate a lot of bug reports, questions, and suggestions. To keep paying users happy, I offer a 1-day response time on support issues, which requires me to spend quite a bit of time sending emails.
Then, of course, if you want to grow the app, you need to spend time marketing it. We could talk for hours about this.
The list goes on and on. Feel free to shoot me an email (email in my profile) if you want to talk specifics about anything.