This is an open source project designed to be hosted on one of the "personal cloud" platforms that you can run yourself on your own hardware, or if you want, run on a VPS that you trust. That eliminates many of the concerns that people generally have about "the cloud," while still giving you the convenience of having it web-accessible from anywhere you want to check it.
Or I can use X11 forwarding over SSH to access GNUcash from my desktop which seems a lot safer than hoping that whatever VPS I have on the Internet is magically secure.