Many lithium cells for critical applications have safety measures built in to prevent a runaway heat excursion. Aftermarket cells or heating coils substituted to gain more amperage in E-Cig are cited for such accidents.
http://www.cigbuyer.com/e-cigarette-fires-explosions-extremely-rare/
True. Not too many kids understand circuits or how to safely modify an electrical circuit. That and they have the immortality attitude, and have no idea just how dangerous tinkering with lithium batteries are. Even with my background I am extremely respectful of that.