There are many reasons to give up smoking in favour of vaping:
Public health England found e-cigarette use is associated with improved quit success rates over the last year and an accelerated drop in smoking rates across the UK
Nicotine itself — either in cigarettes or e-cigs, or other nicotine products — has not been shown to cause cancer. ... Cancers from smoking are caused by the combustion of tobacco.
The latest research by Public health England concluded that there were no identified health risks to bystanders.
But the government doesn't agree!