I'm 23 and I started vaping about 2 weeks ago. I switched more so out of necessity and I'm glad I did. I agree with a few of the comments about why young people are deterred from making the switch, but that's just based on my personal reasons. My reasons for hesitating to switch were:
1.) Initial costs: the high initial costs played a role since I am a college student, but when you take a step back and really calculate out the costs between both, you really do save money in the long run with vaping.
2.) Skepticism: i was REALLY skeptic about it being able to substitute for smoking. i didn't believe it would be able to satiate my cravings for a real cigarette, but was proved wrong when i tried my first pv.
3.) Maintenance and convenience: Vaping takes more work than smoking and i think most young people like things to be easier. It's much easier to buy a pack and light up. With a PV you have to refill carts, clean out parts every so often, make sure you don't flood or burn out your atty, etc.
4.) Delusions of Invincibilty: You're young, you don't feel the after effects of years of smoking cigarettes and you kind of trick yourself. You keep saying you'll quit at a certain time anyway, then when that time comes, you pick another later date, etc. You figure, you're still fine, so why fix something that ain't broke.
5.) Vaping is VERY different from smoking: You have to learn how to inhale properly and differently when vaping versus smoking. Like I mentioned earlier, there's alot more upkeep with vaping than smoking that requires more maintenance, attention, etc. Also, there's so much to learn about vaping and some are discouraged by that.
Again, these were just my personal reasons for why I was hesitant to make the switch, I'm sure some can apply to most young adults, but everyone does have their own personal reasons. =]