Some people will believe it.
Because lies are very powerful tools used by manipulative people to get what they want; and unless and until the lie is exposed for what it is, in a way that proves the innocence of the target of the lie, the lie will continue to be spread through rumor and fear. Often, the target gets shunned and reviled, while the liar sits back and laughs. The victim gets trapped into a corner and seems to have no way to really defend himself/herself without looking as bad as the liar.
And you asked "why?"----sometimes because the liar looks harmless and of course hides the lie under a few truths, so people are inclined to believe them. Remind ya of anyone? Like maybe......Satan!
I hate lies. And I pray to God not to hate the liar. It's very tempting to hate the liar. After all, which of us has not been the victim of a liar? Few of us I bet.
P.S. I'm a conservative, and I'll expose a LIE right now-----the second half of SteveoMc's post!
Shame on you SteveoMc.