I have a spare battery that I carry around. I actually have 4 spare batteries already charged. I only need to swap once per day anyways. The battery itself is super slim, can fit in your shirt pocket. Just takes 15 seconds and I get 100%, meanwhile you're using your phone WHILE it's charging and plugged in... some phones like LG SLOWS DOWN and throttle the speed to avoid overheating.. so you get reduced performance plus a hot battery.. hot battery equals lower battery life expectancy. And no, once you go to a service center to replace your battery (probably costs $100 the cheapest), the phone is no longer waterproof.. so it's not even worth the trouble.
Plus I have a quick charge 3.0 charger in my car.. it charges SUPER fast. If I plan to go somewhere that I know I won't have access to power, I'll bring some spare batteries with me in my pocket.
But dang, imagine if the 30,000 mAh caught fire in an accident.. you're looking at a hand grenade... Plus the metal chassis will scratch and damage your phone if you have it together.
I still love LG and respect their decision to have sealed batteries.. but I'm still benefiting from removable batteries and enjoying the extra freedom.