Yeah, it's strange to come across people saying they keep their assets "offline" when actually their assets are never offline. It's all about the keys.
Andreas Antonopoulos created a lot of great content on this topic. I can only recommend to anyone to watch his older videos on YT. I've learned a lot from Andreas in my early days in this space. Managing my own keys was one of those things.
Thanks for the tip, I might check out this guy.