I've had ideas for side-projects before, but most times I never actually went to building them because I got too scared of holding private data (sometimes sensitive information such as financial data).

I thought of just building offline apps for the browser and letting the user sync data using Dropbox or some competitor, but never found an open source project to facilitate that kind of thing (an actual db that syncs through Dropbox). I also heard that locally storing a Dropbox token in the browser could be dangerous (assuming an offline-app-for-the-browser architecture, for example), which meant I'd have to build actual native apps. But then, isn't it dangerous to store a token in the OS as well?

I might never build a side project. But damn, I wish there weren't bad people willing to steal data out there.