You need to be comfortable using whichever type of battery device you choose. If you're more comfortable using an internal battery mod, then use that.
But you can choose to educate yourself on the removeable batteries. They are a safe
r battery, but you still need to use safe battery practices when using them because there are no "safe" batteries.
There are pro's and con's to each type.
Internal Battery (Lipo) or External Batteries (18650)? Which type is right for you?
I use both mods that use either Lipo and mods that use removeable batteries. My preference is to use removeable batteries because I can pick and choose which model best fits my style of vaping from their battery specifications. You can't do that with internal battery mods, because the manufacturer does the picking.
Battery Basics for Mods: The Definative Battery Guide for Vaping