FWIW - these things fail far more often than EV’s which have far more safety (thermal management/battery management) built in and higher quality batteries.
There is always some level of risk. I am pretty vocal about my opinion that these batteries are not ideal for larger applications such as buses or other heavy equipment, but the highest risks seem to be found in these e-bikes, e-scooters, and sadly now, e-wheelchairs.
Batteries are made up of cells connected in series/parallel to achieve the desired voltage and capacity. There are some crappy cells to be sure, but the interconnects are done with welded nickle straps and after a few bounces, they can break and connect things that shouldn’t be. All lithium chemistries require battery charge management (BCM) circuits and if the controller can’t tell what’s happening in a particular cell or string it can overcharge, and bad things can happen.
You forgot the Segway device battery fires