The IQOS unit heats the tobacco to a precise temperature at which it vaporizes the tobacco but doesn’t combust. The result is much like the vapor you get usingportable cannabis vaporizerslike a PAX or Firefly, which also use conducted heat to extract the contents of plant material. However...
It may simply be an experience too unlike smoking for them to get used to. After all, no vaping product actually tastes like burning tobacco. And with vaping, there is no defined beginning or end to the experience: smokers light a cigarette and then put it out a few minutes later, but...