I started e-cigs to stop smoking and I did. Though some people have a transition period where they do both while finding the will or the right equipment or the right juice to replace smoking completely, I think the majority of people here transitioned pretty quickly from smoking to only vaping, and some of those only bought the e-cig out of curiosity with no real intent to stop smoking, yet they did.
But it does require decent ecig hardware that is strong enough and economical enough. There are a lot of crap ecigs out there being sold by unscrupulous "name" brand vendors who care about nothing other getting a person's money and locking them into their particular weak or unaffordable system.
I researched here first, made a decent choice for my own needs, and after smoking 1.5 packs a day for several decades I switched easily to vaping. Now I am not inhaling 4000 chemicals and carcinogens, I am not causing second hand smoke, my sinuses cleared up, I can breath better, food tastes better. And I also plan to lower my nicotine habit which will be easier with vaping than with cigarettes.