I can’t speak to OP’s claim about former smokers. However as a younger person who knows many younger never-smoker vape users, I can attest that they all consume vastly more nicotine than would ever be practical with cigarettes.

Vape pods are highly concentrated and you can use them anywhere, any time. No more need to bother with sneaking out of the house or taking smoke breaks.

Here's a start - feel free to go off on your own and learn.

https://www.hopkinsmedicine.org/health/wellness-and-preventi...

"What’s worse, says Blaha, many e-cigarette users get even more nicotine than they would from a combustible tobacco product: Users can buy extra-strength cartridges, which have a higher concentration of nicotine, or increase the e-cigarette’s voltage to get a greater hit of the substance."