I get it all the time, and people seem to lay off when you clear up a HUGE misconception about both smoking and vaping. NICOTINE DOES NOT CAUSE CANCER!! I've found that an overwhelming amount of non-smokers assume that nicotine is the most harmful part about smoking, and that even alone, it causes cancer.
Generally, once i explain to people that nicotine alone is very similar to caffeine, and that it is not a carginogen, and it is not what's harmful about cigarettes (it just keeps you inhaling what IS harmful), they generally are more accepting. I feel like that's been one of the biggest suprises in telling people about vaping is they think nicotine is what causes cancer in cigarettes.