Seems like a good time to highlight this video from Grin Technologies and their experience with ebikes over the years.
https://www.youtube.com/watch?v=j92Gt4VviSQ
Summary Statement: He summarizes the results of the "sabotaging" attempts by saying, "we just couldn't for the life of ourselves get a nonprotected modern lithium battery to do anything" [02:40:27], in terms of causing a fire. (referring to 18650s)
There are certainly problems out there with cells but it was a surprising statement from someone with a ton of real-world experience. Also they are a very conscientious company so they don't deal with dodgy stuff if they can avoid it.
replies(2):