AFAIK that's not really true, at least of modern vapes. Their function is not to "make fire", it's to heat a metal coil to a specific temperature at which propylene glycol and vegetable glycerin will aerosolize which is far lower than ignition temperature. Most modern vapes also use controllers with a feedback loop that pulse power through the coil hundreds of times per second to maintain the ideal temperature and desired power throughput. That being said there are definitely crappy and diy devices that unsafely dump huge current through devices but AFAIK modern devices generally don't do this because it's a bad user experience (burnt taste, too hot, ruined cotton absorber, etc) -- regulating the power is what users want so it's what devices do.