If someone lands on your website for the first time, the likelihood is, they won’t buy. Not straight away.
Before they get to the point where they feel comfortable enough to buy from you, they need to know, like and trust you first. But you can’t guarantee they’re going to keep returning to your website, right?
That’s why you need to collect your users’ data, so you can contact them (usually via email) and nurture them to a point where they feel comfortable enough to buy from you.