Strangers are justifiably suspicious.
Friends give you the benefit of the doubt.
“Friend” is more broadly defined as someone you have a beer with or meet up with to go on a hike. A friend is someone who has interacted with you, or who knows your parents or reads your blog—someone with history. If you’ve made a promise to someone and then kept it, you’re a friend. If you’ve changed someone for the better, you’re a friend as well.
We market to friends very differently than we market to strangers. We do business differently as well.
Thanks to social networks and the amplification of stories online, we have far more friends per person than at any other time in human history. Nurturing your friends—protecting them and watching out for them—is an obligation, and it builds an asset at the same time.
(I want to distinguish friends from 'friendlies', the people you have a digital link to, but no real connection. Friendlies are basically strangers with a thumbnail of their face on your screen. They're not friends. And, while we're at it, the moment you treat a friend like a stranger (form mail, for example) they're not a friend any more, are they?)