Don't do it your phone will turn into a nuke. jk.
Those very common comments can be very misleading as they usually over exaggerate or use the terms for something else that is not actually what it sounds like. For example... they are all pretty similar but here's one; "My phone died and the jailbreak is gone." Your phone cannot just just 'die' from software not being bootable, that would be extremely bad software design. Sure it is possible to lose your jailbreak as in it will not boot cause something has changed system files and it cannot boot in its current state, but that is more and more unlikely as less tweaks modify system files (so incompatibility doesn't effect future or other OS versions) for that reason. Even if they manage to get them selves into that situation somehow by not thinking smartly then it is easy as connecting it to iTunes and going to the latest version of iOS (stock).
Simply put, as long as you aren't stupid and create the risks there isn't really going to be risks that come to you incidentally.
There aren't many likely risks, you should be fine, however because you are on the version the exploits were patched on and you aren't already jailbroken and have saved the blobs you cannot downgrade as that is the requirement to do so.
Your options: Buy a device on iOS 12.0 ~ 12.1.2 (for iOS 12 jailbreak) or wait till the iOS 13 jailbreak comes out.
It would be best to either stay on the version you are on to wait for a jailbreak on that version if exploits don't work on iOS 13 they may be released and used on iOS 12. Otherwise go to iOS 13 when the first public release releases and stay on it and wait for a jailbreak. You can update to a later more stable version after the jailbreak comes out as long as you save your blobs (for every version preferably). It's your choice whichever you think will get a jailbreak first.