Where did bedbugs come from?

Almost everyone I know is having a bedbug problem! I'm afraid of bugs. Especially spiders! So I don't make visits to any body's house that tells me they have an infestation. I've done some research on bedbugs. It's really scary to me. A bug waits for you to go to bed, and crawls all over your body sucking your blood! I use to be deathly afraid of spiders, but now I see that spiders serve a way better purpose rather than the bedbug, What purpose do bedbugs serve on earth? Anybody else having bedbug issues? please share. I'm afraid that my home will become infested.