We need to understand that these batteries have a very thin margin of safety. The cathode, anode, electrolyte and other components are sandwiched with all materials in very close proximity. A short is just a tiny flaw away at any given moment. The growth of just one large dendrite can short out a cell. Or for that matter, an overheated or just slightly imperfect cell can easily fail.
The idea that the statistical risk is low, is incorrect. The risk increases with time, cycles and abuse.
There is a reason Tesla’s cells are the most reliable. They take great pains to ensure a stable environment for the components, while not pushing the electrolyte thinness limits. In fact the Honda/Yuasa cells used in hybrids have extra robust components. These can take many more cycles, and have much lower energy density.
I’d just tell him some of us work for a living. If he has bankers hours that work out for him to do so, good for him.
