I've been vaping 18mg/mL nicotine every single day all day for 2 years and have also used gum/lozenges but whenever I'm back with family and can't use nicotine (they wouldn't approve), I literally never get any withdrawals. Maybe I miss the feeling of having something in my mouth or holding in my hand but even a fidget spinner takes care of the latter problem.

Am I somehow immune to nicotine addiction? I've been able to stop cold turkey several times now while all my friends struggle with getting off of it. Meanwhile I voluntarily use it since it's fun. What's the science behind this?